The prosecution theory in the Scott Peterson case is that Scott dumped the body of his wife in San Francisco bay, weighed down by concrete anchors.
An appeal brief summarises the search of the bay like this:
As discussed more fully below, the state searched the bay for weeks and weeks looking for the anchors but found nothing. (64 RT 12644-12645; 65 RT 12709-12710, 12779, 12786-12787; 66 RT 12813-12825, 12837.) Police used dive boats, sonar, a special underwater search vehicle and specialized dive teams from the FBI, Contra Costa County, Marin County and San Francisco County. (64 RT 12644-12645; 65 RT 12786-12787; 66 RT 12819-12820.) Because they found nothing at all, the state was left with pictures of concrete dust to prove that five anchors had been made.
To understand how unlikely it is that the search could have failed, it helps to examine the testimony in more detail. Full transcripts are available here ( Prosecution Witness #69: Rick Armendariz, MPD ) and here ( Prosecution Witness #75: Henry Dodge Hendee, MPD Detective ). but here are some extracts:
GERAGOS: Well, there were other searches. There is a lot of garbage down there. They brought the garbage up, correct? Back in September they brought up a number of items that were garbage, correct?
GERAGOS: Beer bottles, tea glass bottles, small items of garbage were brought up repeatedly from the bay floor by the divers, correct?
GERAGOS: The third location the divers found a wooden stick, right?
ARMENDARIZ: You are referring to F45. And that’s correct.
GERAGOS: How big was this wooden stick?
ARMENDARIZ: There is a photograph of it on 33096. And it was F45.
GERAGOS: How big would you estimate it to be?
ARMENDARIZ: There is a ruler in the photograph, which is a foot long. And looks like it’s approximately foot and half, possibly about two feet long.
GERAGOS: So apparently the, whatever, however you got these targets, the divers were able to find pieces of wood that were a foot and a half long, correct?
ARMENDARIZ: Correct. They went to the dive location. And in that general dive location was a piece of wood that they found.
GERAGOS: Okay. And they went down looking for a target, and after ten minutes they came up with a tea glass bottle?
GERAGOS: How big is the tea glass bottle?
ARMENDARIZ: It’s photographed in 33026. And it’s a standard, this is an estimate, approximately twelve-ounce tea bottle, glass tea bottle.
GERAGOS: When you say standard, like a Snapple bottle?
ARMENDARIZ: No, it was a little larger than a Snapple bottle.
GERAGOS: And apparently they were able to, divers were able to find that on the bottom of the bay floor?
ARMENDARIZ: They recovered that from the bay.
GERAGOS: And so they found there was a target area, somebody was able to, either through side-scan, or through mapping, or something, to find something on the floor and they found a blue square bucket, right?
ARMENDARIZ: Blue square bucket was the item that was recovered by the dive team that brought that up to the boat, correct.
GERAGOS: How about the A15? What is that?
ARMENDARIZ: A15 was another bucket that was recovered from the dive team.
GERAGOS: Okay. A7?
ARMENDARIZ: A7 was a beer can that was located.
The second witness, Hendee, explained the scope of the search:
HENDEE: No. They’re far apart. What I started to say was that the operation that we set up, we tried to search a grid one and a quarter miles in length across and one and three quarters of a mile down. If you try to, in terms of trying to understand how big that area is, it’s 21 football fields across from end zone to end zone. If you lined one up after the other, that’s 21 football fields by 39 football fields down. You take that and you make that your perimeter, and that’s a huge area to cover. And that’s what these people were trying to do. We broke them down into quarter mile grids, and each agency that had a side-scan sonar operator searched those grids with their side-scan sonar device. And if they found an object, then we had dive teams standing by to go in and try and recover whatever object that they saw on the side-scan sonar.
HARRIS: How many divers would go out at any particular given time?
HENDEE: It all depended, on the, if we’re talking about the May 16th through May 23rd operation, I’d have to check each individual officer’s reports to find out how many were on their particular dive boat. The FBI dive team probably had six divers, maybe eight operating on an every day basis. The spot divers that would go down when a side-scan sonar operator found something, depending on how many were on that boat, and I don’t know for sure how many were on any particular dive boat at that time, but the entire operation that we were running over this eight days was averaging about 45 to 50 people a day, total, in the operation.
JUDGE: Does that include all the divers?
HENDEE: That included the divers, the boat operators, the Coast Guard personnel. Everybody.
GERAGOS: So that we all understand, when they are traversing this, what they are actually doing is going down on one side, and as far as you know, the REMUS device actually will take images so that they mapped the entire bottom of the bay floor that it covers; isn’t that correct?
GERAGOS: Then the machine, as far as you understand, can piece together each of those little images so that you get a mosaic, that when you look at it all together, I suppose if they could do, that if you had a large enough screen, you could see, you would have a map of the entire area here; isn’t that correct?
HENDEE: I don’t know if they have that equipment. But if you could put it all together, you would he have a mosaic. Problem with that, though, is, it covers a hundred fifty percent coverage area. So you would have to put one picture on top of the other a little bit, because that’s what you are getting, a hundred fifty percent coverage.
GERAGOS: So that we understand, and when you say a hundred fifty coverage area, you have got the coordinates here, right? What I’m pointing to. There is four of them; is that correct?
GERAGOS: Now, out of those four coordinates, you say a hundred fifty percent coverage area. Do you mean that it goes a little over fifty percent this way? Do you mean as they are going up and down, that they are actually kind of slopping over into the next area that they are going to cover?
HENDEE: It spans a little bit of the next area so that you are actually, you are not missing any areas. You are going up. You are turning. It comes back down, and it’s covering part of what it had just seen the last lap.
GERAGOS: Not only are you not missing any areas, you are covering the same square twice.
HENDEE: Right, yes
To summarise, the search was systematic, the searchers made a complete map of the floor of the bay area where Scott could have dumped Laci’s body, with 150% over-lapping coverage, and objects as small as a beer can or small glass bottles could be located and brought to the surface. The only reasonable conclusion that can be drawn is that Laci Peterson’s body was NOT on the bottom of the bay for several months, weighed down with concrete anchors, as the prosecution claim. Instead, something else entirely occurred.