Conner's Age Proves Scott's Innocence


Laci was known to be alive at 8:30 p.m. on the night of December 23, and Scott is known to have left home for the Warehouse at no later than 10:08 a.m. on the 24th. Therefore, the State had to prove that the murder happened in that time frame: 8:30 p.m. --> 10:08 a.m.  In his Closing Argument, Rick Distaso identified the time of death on which the State rested its case:

It's very simple. The defendant strangled or smothered Laci Peterson the night of February, January, December 23rd, or in the morning while she was getting dressed on the 24th. I can't tell you when he did it. I can't tell you if he did it at night. I can't tell you if he did it in the morning. I'm not going to try to convince you of something that I can't prove. I don't have to prove that to you. I only have to prove that he did it.

Laci's body yielded only a generalized 3-6 months estimate for time of death, insufficient to establish beyond reasonable doubt that Scott murdered her within the right time frame. The burden of proving time of death thus fell on baby Conner's shoulders.


Establishing time of death for Conner relied on two critical pieces of information: 

The State argued that the facts prove Conner died between the required time span:  8:30 p.m. December 23 --> 10:08 a.m. December 24.  Dr. Greggory Devore was called as an expert witness to present this to the Jury. 

Devore's credentials are outstanding, and he is well-recognized in his field.  His expertise is in maternal-fetal medicine, which is caring for the mother or the fetus that may to be at high risk. This involves using ultrasound as one of the primary tools for evaluating the fetus.  During the course of his career, he has performed over 75,000 ultrasounds.

Devore's first task was to determine Conner's gestational age on December 23, 2002.

  1. He reviewed Laci's medical records and noted that the gestational age from the 1st ultrasound, the gold standard, deviated only one day from the gestational age from Laci's last menstrual period (LMP). He assumed that the gestational age from the LMP was absolutely accurate. The LMP yielded a gestational age of 33w1d on December 23.

  2. He consulted Laci's medical records and noted the femur bone measurement of 32mm taken on September 24, 2002, as part of the 2nd ultrasound.  He consulted Philippe Jeanty's studies on fetal biometry and noted that Jeanty places this measurement right at the 50th percentile.  Devore noted the absence on Laci's medical records of any pathological factor that would keep Conner from developing at the 50th percentile.  He assumed Conner continued to develop at the 50th percentile and was at the 50th percentile when he died.

With Conner's December 23 gestational age established as 33w1d, he proceeded to determine Conner's gestational age at the time of his death, and, in the process, determine the date of death. 

  1. He obtained the femur bone that was removed from Conner's body, placed it in a water bath, and used his portable ultrasound machine to take three measurements, which were:  64mm, 64.7mm, and 65mm.

  2. He consulted various fetal biometry studies to determine gestational age for these measurements, based on 50th percentile.

  3. He calculated dates of death by comparing these gestational ages to the 33w1d gestational age from the LMP.

  4. He relied most heavily on Philippe Jeanty's studies, which produced the following gestational ages and corresponding death dates:


    64mm = 32w6d = December 21

    64.7mm = 33w1d = December 23

    65mm = 33w2d = December 24

Devore thus proved that Conner died between the critical time period:  8:30 p.m. December 23 --> 10:08 a.m. December 24.


It all sounds so logical, so compelling.  That's the problem.  His credentials give him the appearance of knowing what he is talking about. The fact of the matter is, Devore employed junk science to give the State the results it wanted.  His methodology is brand new and has never undergone peer review.    His conclusions are contradicted by all the other experts that testified -- Laci's doctors, the forensic pathologist, the forensic anthropologist -- and he is contradicted by several fetal biometry studies.  Even Jeanty contradicts Devore's conclusions.


Two facts he did get right -- the December 23 gestational age derived from Laci's LMP is indeed 33w1d.  And Jeanty does put the 32mm femur bone measurement at the 50th percentile.  Everything else, however, is simply data manipulated to yield the necessary results.


An examination of Laci's medical record and consultation with fetal biometry studies establishes well beyond reasonable doubt that Conner lived at least a week beyond December 23, and that fact fully exonerates Scott Peterson.


Conner's gestational age on December 23 was 32w1d, according to Laci's Medical Records

Laci's own doctors determined the gestational age long before it became a matter of evidence in a capital murder trial.  Her doctors had nothing but Laci's and Conner's well-being in mind when they made their age estimations.  For that reason, their observations are totally objective and not biased towards either the State or Scott Peterson.

Let's follow the evolution of Conner's gestational age as recorded on her medical record.

1st gestational age -- LMP

When Laci started going for pre-natal examinations, a physician's assistant calculated her due date, technically known as the EDC (estimated date of confinement, or due date), through the use of a Pregnancy Wheel.  This wheel simply computes the estimated date of delivery by adding 280 days to the first day of the last menstrual period -- that's what LMP stands for, last menstrual period.  This is an antiquated but common practice.  Accordingly, her EDC was set at February 10, 2003.   A Gestational Age Calculator does the same thing, but a Pregnancy Wheel is easier to use.   Click here to view a Pregnancy Wheel online, and experiment by selecting different dates for LMP.  If you click May 6, you will get February 10 as the due date.

This put Conner's GA on December 23 at 33w1d.

2nd gestational age -- 1st ultrasound 

The first ultrasound, taken sometime around 7-9 weeks, is relied on to correct the EDC derived from the LMP, if necessary.  Laci's 1st ultrasound was taken on July 16, when she was 10w2d according to LMP, a little past the ideal time of 7-9 weeks.  The results of the 1st ultrasound dated Laci's pregnancy at 10w1d, with a standard deviation of ± 5 days.  Since it was only 1 day off from the EDC established by the LMP, Laci's due date remained February 10.

This put Conner's gestational age on December 23 at 33w0d.

3rd gestational age -- 2nd ultrasound

The second ultrasound is taken between 12 and 20 weeks to be sure that the baby is developing normally and to correct the EDC, if necessary.  Laci's was taken on September 24.  Instead of the 20w2d (LMP) or 20w1d (1st ultrasound) for gestational ages, the four measurements Dr. Yip took indicated the following: 

Abdominal circumference (AC) 134 = 18w3d ± 14 days

Head circumference (HC) 163 = 19w0d ± 11 days

Biparietal diameter (BPD) 45 = 19w4d ± 10 days

Femur length (FL) 32 = 19w4d ± 6 days  

Dr. Yip settled on 19w2d as the gestational age, and noted a corrected EDC of February 16, 2003. 

This put Conner at 32w1d on December 23.


The State argued that Laci's doctors did not change her EDC to reflect the 2nd ultrasound, thus downplaying it's importance.  David Harris elicited the following testimony from Dr. Tow-Der:

David Harris: The -- when they're only six days apart, do you change the estimated due dates based on that?

Esther Tow-Der: For clinical purposes we usually base it on the original due date, if it's within seven days. Which in this case was 2/10/03.

David Harris: So it's really -- there's kind of a window; babies are going to come when they decide to come, and within six days that's pretty close to a normal range for pregnancy?

Esther Tow-Der: Very normal range.

However, the notations Dr. Tow-Der made on Laci's chart show otherwise.  Click to enlarge.



This chart shows the gestational age according to the 3 different calculations and what was recorded on Laci's chart for each pre-natal visit.  The last 2 notations were by Dr. Tow-Der and do indeed reflect the corrected EDC.  Once the first ultrasound is taken, it dictates the gestational age written on the chart.  The September and October likewise are based on the 1st ultrasound.  However, both November and December are based on the 2nd ultrasound, rounded off to the week.  Click here for a calendar that shows the critical days marked.


DATE Day/Pregnancy EVENT


Recorded on CHART


1st u/s 2nd u/s
May 6 Day One 1st day of Last menstrual period        
Jul 16 Day 72 1st sonogram 10w2d  10w1d   10w1d
Aug 20 Day 107 pre-natal exam 15w2d  15w1d   15w1d
Sep 24 Day 142 2nd sonogram 20w2d 20w1d 19w2d 20w1d
Oct 29 Day 177 pre-natal exam 25w2d 25w1d 24w2d 25w0d
Nov 25 Day 204 pre-natal exam 29w1d 29w0d 28w1d 28w
Dec 23 Day 232 pre-natal exam


33w0d 32w1d 32w


The State had no rational reason for rejecting the judgment of Laci's doctors, which is that Conner was 32w1d gestational age on December 23, 2002, not 33w1d, as Devore insisted.


Fetal Biometry Studies confirm the wisdom of the corrected EDC


When Dr. Yip conducted the 2nd sonogram, he had the option of choosing which study to use as the standard.  He chose the 1981 study by Hadlock.  However, other fetal biometry studies confirm the need for a corrected EDC.


Biparietal diameter 45mm  

Yip's standard (Hadlock) = 19w4d.   Jeanty = 18w6d.  Campbell agrees with Jeanty, and  Sabbagha and Wexler are both at 19w. Interestingly, Jeanty, Devore's favored reference, is the youngest of them all. 



Head Circumference 163mm

Yip's standard (Hadlock) = 19w0d. Jeanty = 18w5d.  Deter agrees with Jeanty and Ott is under 20 weeks.  Once again, Devore's favored reference, Jeanty, yields the youngest gestational age. 

Abdominal Circumference 134mm

Yip's standard (Hadlock) = 18w3d; Jeanty = 18w1d.  Tamura agrees with Jeanty, and Deter is under 19 weeks.  Once again, Jeanty yields the youngest gestational age.


Femur length 32mm


Dr. Yip's Standard (Hadlock) = 19w4d.  Both Hohler & Quetel studies are under 19w4d.  Only Jeanty yields an older age, 20w1d.


Femur Length

Hohler & Quetel



Hohler & Quetel



32mm 18.7 (18w5d) 20.1 (20w1d) 19.4 (19w3d) 19.6 (19w4d)

Source: Estimation of Gestational Age from Measurements of Fetal Long Bones, P. Jeanty et al.

  J Ultrasound Med 3:75-79; February 1984, pg. 7.


We can get a better view of how the fetal biometry studies support Dr. Yip's decision to change Laci's EDC by six days through this chart. 

















diameter 45mm











head circumference 163mm











abdominal circumference 134mm











femur 32mm











Dr. Yip's conclusion 19w2d Change EDC from February 10 to February 16



Out of 17 gestational ages, Jeanty's femur length is the ONLY one that corresponds to the LMP of 20w2d and the 1st ultrasound of 20w1d.  The only one out of 17.  And 3 out of 4 measurements for Jeanty put Conner's gestational age even younger than the 19w2d age Dr. Yip decided upon. 


To favor the femur length measurement to the exclusion of 16 other measurements is not good science.  Moreover, that is not what Jeanty himself would do, since he places more reliance on the biparietal diameter measurement at this stage in the pregnancy than on the femur measurement.  In "Estimation of Gestational Age from Measurements of Fetal Long Bones," he notes the two standards for determining gestational age in the first half of the pregnancy:  the crown-rump length, maximum accuracy from seven to nine weeks; and the biparietal diameter, maximum accuracy between 12 and 20 weeks.  Only in the latter half of the pregnancy do the fetal long bones, including the femur, have the potential to yield more accurate gestational ages than the biparietal diameter.  Still, Jeanty insists that using only one long bone will not yield mathematically valid results.  Rather, the four long bones -- humerus, tibia, ulna, and femur -- should all be measured and the average taken to derive the gestational age. (J Ultrasound Med 3:75-79; February 1984, pp. 75, 78) 


In Conner's circumstance, the biparietal diameter measurement was taken during the maximal accuracy time period, and therefore there is no justification to disregard it in favor of the femur measurement, especially when the other 2 measurements taken yield gestational ages even younger than the biparietal diameter, and every other study suggests a younger gestational age for the 32mm femur measurement than Jeanty does.


Fetal biometry studies clearly support Dr. Yip's judgment -- Conner was six days younger than indicated by the LMP and he corrected her EDC to reflect that.  The best estimate for his gestational age on December 23 was 32w1d.  Dr. Tow-Der acknowledged this by noting 32w on Laci's medical chart.


Conner's gestational age at time of death


The State did not accept 32w1d as Conner's gestational age on the 23rd because, as we shall see, every indicator showed that Conner was older than 32 weeks when he died, automatically excluding Scott Peterson as the person responsible for his death. 


External observations


Full-term is characterized as between 38 weeks and 42 weeks. 

The American College of Obstetricians and gynecologists considers full-term any infant born after 37 completed weeks of gestation. The World Health Organization considers full-term any infant born after 38 completed weeks of gestation. (Source)

On December 23, Conner was still at least 6 weeks from full-term.  However, without exception, every person who observed Conner, described him as a full-term baby or nine-months. 


From Media Reports:

On Sunday, a tip led Richmond police to the body of a baby that had washed ashore near the Richmond marina. The body was discovered about 4:45 p.m. near Seabreeze Drive, police said.
The woman's torso was found less than two miles away from where dog walkers came across the body of a baby with its umbilical cord still attached. The body, found in the grass near the water, was badly decomposed.
The coroner's office said the newborn was a full-term baby boy.
Contra Costa Times, Monday April 14, 2003 


East Bay Regional Park police contacted Modesto police after a body was discovered near the Point Isabel Regional Shoreline Monday. Jimmy Lee, spokesman for the Contra Costa County Sheriff’s Department, said he was told the body belonged to an adult female.
Sunday, the Richmond Police Department responded to a discovery by two people walking their dog, a dispatcher with the Richmond Police said. Those people found a "full-term male child," Lee said.
ModBee, April 15, 2003


A woman's body was found today on a rocky shore in Richmond, Calif., a day after the body of a full-term male fetus was found in an area police have searched in the past for Laci Peterson, a pregnant woman who vanished Christmas Eve.
A dog walker found the woman's body at the Point Isabel Regional Shoreline in Richmond, police said. The fetus was found Sunday, about a mile away. The Contra Costa County coroner said the fetus was a full-term male and still had the umbilical cord attached., April 14, 2003

Authorities investigating the disappearance of 28-year-old Laci Peterson were called to the scene because it is an area where Modesto police searched by boat for the missing pregnant woman's remains, and a full-term baby boy's body was found in the same area on Sunday., April 14, 2004


Richmond Police Sgt. Enos Johnson said the woman's remains were "skeletal," and that the coroner has determined that the baby, found Sunday about a mile north of the woman's body, was a full-term boy., April 14, 2003


Police are investigating whether a badly decomposed body that washed up yesterday at a park on the shore of San Francisco Bay is that of Laci Peterson, the pregnant woman who disappeared from her Modesto, Calif., home on Christmas Eve.
A day earlier, the corpse of a baby boy, described by authorities as a full-term fetus - with its umbilical cord still attached - had been found on a trail a mile away, fueling suspicion of a Peterson link.
From NY Post, April 15, 2003


The discovery of the woman's remains came one day after a passerby spotted a tiny body near the Richmond Marina, about a mile to the north. Police identified it as a "full-term" fetus. LA Times April 15, 2003


A full-term, decaying male fetus with the umbilical cord still attached was found Sunday, about a mile away, according to the Contra Costa County coroner. Police sources told ABCNEWS the amount of decomposition and size of the remains are consistent with the time frame of Peterson's disappearance and her physical description, and that a nursing bra typically worn by women during late-term pregnancy was found on the remains., undated.

From the testimony of Dr. Brian Peterson, Medical Examiner who performed the autopsy:

Mark Geragos:  Okay.  Did you ever tell Detective Grogan -- and it looks like he interviewed you on Monday, April 14th, at about 3:15.  Is that -- I know you probably talked to a number of people regarding this case.  But did you ever tell him that the baby was a full-term male infant with advanced stages of decomposition?  

Brian Peterson:  That's just what I described in the report.  

~~Prelim Hearing Testimony~~

Mark Geragos: And you, you also characterized in your report, did you not, previously when you've testified, that the baby appeared to you to be a full-term baby; is that correct?

Brian Peterson: Correct.


Mark Geragos: Okay. And when he first came in and you saw him just alone, you had estimated him as actually having been, what, a nine month fetus? Or as actually as a full-term infant? Or was there no difference for you?

Brian Peterson: Well, what's "term"? 280 days. So depending on how one measures, and based, again, only on the crude measurement that I could do, nine months and/or term.


David Harris: You were also asked about your determination of age of the body of Conner Peterson. And go to that real quick. Did you list, under autopsy diagnosis, a particular gestational age for Conner Peterson?

Brian Peterson: On the first page of my report, I'll read to you. I said estimated gestational age, nine months.

~~Trial Testimony~~

From the testimony of Jeffrey Soler, Richmond PD Evidence Technician

Jeffrey Soler: The only reference that it makes to it is his (Dr. Peterson's) comment that the baby may have reached full term. There is no other, I have no other recollection of whether he was able to say that the baby was born alive or not.

Mark Geragos: Now when you say, what does "the baby may have reached full term" mean to you?

Jeffrey Soler: All we're talking about is the age of the baby.

Mark Geragos: And that would have been nine months?

Jeffrey Soler: Thats correct.

From the testimony of Craig Grogan, Lead Detective MPD

Mark Geragos: Okay. Okay. And Doctor Peterson and you had a conversation after he had examined the baby as well and done the autopsy, right?

Craig Grogan: Yes.


Mark Geragos: And he also said that he believed that the baby fell within a nine-month-old infant range?

Craig Grogan: That’s what he said.

Mark Geragos: And that if you wanted to say that it was seven and half months old, it would be a somewhat large baby, correct?

Craig Grogan: Yes.

Forensic pathology


Dr. Brian Peterson, the Medical Examiner who performed Conner's autopsy, is a forensic pathologist employed by the Forensic Medical Group in Fairfield.  As part of the autopsy, Peterson took two measurements, the crown-rump length and crown-heel length.  The crown-rump measurement of 32 cm indicated Conner's gestational age was 9 months.  Peterson did not give the details of the crown-heel length in his testimony.

Brian Peterson: The crown-rump length, from my report here, was 32 centimeters.

Mark Geragos: How many inches is that?

Brian Peterson: I'm sorry?

Mark Geragos: How much inches does that translate into?

Brian Peterson: About 15.

Mark Geragos: Closer to 17?

Brian Peterson: Seventeen. There's 2.54 centimeters per inch, but I wasn't a math major.

Mark Geragos: Okay. The, the, and then is there a chart that you then use to show to convert to the number of months?

Brian Peterson: There was.

Mark Geragos: Okay. And that chart put the baby's age at nine months; is that correct?

Brian Peterson: Correct.

~~Trial Testimony~~

Forensic anthropology


Dr. Alison Galloway, forensic anthropologist, is the person Dr. Brian Peterson relied on to more precisely determine Conner's GA, as that is her field of expertise:  a Masters with specialization in forensic anthropology, a PhD in anthropology with specialization in skeletal biology, and certification as a forensic anthropologist on the American Board of Forensic Anthropology. 


Galloway described the 2 reference standards she used, and that she preferred the Sherwood standard because it is American-based, hence drawing upon people with the same factors as Conner.

Alison Galloway: Yes, there is. The most commonly accepted one has been Fazekas and Kosa, which is a Hungarian or Romanian. I believe it's a Hungarian book. It's from 1978. And the sample sizes are based on Eastern European population. More recently, Sherwood, et al, which is another publication, came out in 2001. Came out. And that was using radiographic means of looking at the skeleton. They compared the radiographs to skeleton measurements and other publications. That I used, because it's drawing upon people of the same background, same nutritional levels as what we would see in the United States.


Alison Galloway: Yes. There are some things that suggest that environmental factors, the mother's environment, can affect the growth of the baby. So in areas where you have poor food, lots of disease, children tend to be born shorter because they have less nutrition they can draw from the mother. It's important to use studies that are similar to the population from which you are examining the body.

~~Trial Testimony~~

This is Galloway's table of measurements and the estimated gestational age that results from each of her measurements (Defense 6U).  Sherwood's GA's are in the last column, under the handwritten Sherwood.

This is devastating to the State's case because ALL measurements indicate a GA of at least 34 weeks, and the preferred standard puts Conner at 35.1 to 36.3 weeks.  Laci's medical chart said Conner was 32w on December 23 (precise age was 32w1d).  That puts Conner's death date 3-4 weeks later.  That fully exonerates Scott Peterson.


Galloway's next step was to tack on one standard deviation at each end of the range for Sherwood.

Alison Galloway: You find differences in almost everybody. People already classified as normal will range from the size of, say, Danny Devito and Michael Jordan. They are all normal people. There is nothing abnormal, medically wrong with them. They are just either short or tall. And so that is also reflected in babies. Also, babies grow. They have growth spurts the same as children do. So they grow very rapidly for short periods of time, and then have periods where they are the same size, and then grow very rapidly. This could be a matter of just a few days. So where we catch them in that growth makes a difference where they are in the profiles.

David Harris: So, again, taking that to consideration of how babies and people are different even at the same age, do you have to come up with a range for an individual?

Alison Galloway: Yes. What we do is, we take usually about a one standard deviation. That would put the 33 to 38 weeks. This would include the majority of children who are examined at that age would be within that range of length of the bone.

David Harris: So the ultimate conclusion, based on your examination of Conner Peterson's remains, were his age that you reported back to Contra Costa County was 33 to 38 weeks?

Alison Galloway: That's correct.


Alison Galloway: Yes. That is out of the study. They said one standard error on this was two weeks. Two standard errors includes 95 percent of the population as four weeks plus or minus.

Mark Geragos: So if I understand correctly, when you actual did the measurements the baby came back at all three measurements a -- between 35 to 36. And then when you came to your conclusion, what you did is, you put a two-week window or kind of a cushion on either side of the 35 to 36?

Alison Galloway: That's actually the protocol for the study.

Mark Geragos: So am I correct, you went this -- 35 to 36 on the measurements?

Alison Galloway: Yes.

Mark Geragos: Put two weeks on 36 to get you to 38, put two weeks on the 35 to get you to 33?

Alison Galloway: That's correct.

~~Trial Testimony~~

Adding in one standard deviation puts Conner's GA at 33w for the youngest he could be.  That is one week beyond the 32w written on Laci's medical records for December 23 (the precise age was 32w1d, abbreviated to 32w).  That exonerates Scott Peterson.


During the cross-examination of Dr. Charles March, David Harris asked this pointed question:

David Harris: So you would agree that Dr. Galloway is in a far better position to give an opinion about her estimate of bones and the date of the death based on her examination than you are?


David Harris: So, to go back to my question, would you agree that she's far more qualified to give an anthropologic opinion than you are?

~~Trial Testimony~~

But it is the State that resolutely refused to accept Dr. Galloway's opinion, because it clearly exonerates Scott Peterson.  Adding six days to the 32w1d indicated on Laci's medical chart on December 23, 2002 results in a death date no earlier than December 29, 2002. 

What we have in a nutshell are three experts employing credible scientific procedures to determine Conner's gestational age:

Dr. Yip, Laci's physician, who performed a routine 2nd ultrasound on September 24 that yielded younger than expected gestational ages and adjusted Laci's due date accordingly. 

Dr. Tow-Der, Laci's examining physician, who recorded 32w on December 23, 2002, based on Laci's pre-natal examination and other information on her medical chart.

Dr. Alison Galloway, who took 11 different measurements, used two different reference sources, and applied one standard deviation to the favored reference source to conclude that Conner was 33 to 38 weeks old when he died. 

And the results fully exonerate Scott Peterson. 


Conner, in the judgment of Laci's doctors, was 32w1d (32w written on her chart) on December 23.  Several fetal biometry studies concur with Dr. Yip's decision to change Laci's due date by 6 days. In the judgment of the forensic pathologist and forensic anthropologist, Conner was from 33-38 weeks old when he died. Therefore, he lived at least one 6 days beyond December 23. That fully exonerates Scott Peterson.

To refute the irrefutable, the State employed Dr. Devore.  Devore used a methodology that has never been subjected to peer review and favored a single measurement to the exclusion of 16 other measurements.  Devore's favored study, that done by Jeanty, does not prove that Conner died during the critical time period -- 8:30 p.m. December 23 --> 10:08 a.m. December 24.  For 3 out of the 4 measurements taken by Dr. Yip during the second ultrasound, Jeanty produces younger gestational ages than the standard Yip used.  For the most critical measurement, the biparietal diameter, Jeanty produces a younger gestational age than the standard Yip used.  Devore distorted the data by ignoring the 95% that does not produce the necessary results.  That is junk science.