considerable circumstantial evidence that prosecutors presented was the fact that Peterson changed his appearance and purchased a vehicle using his mother's name in order to avoid recognition by the press. He added two pornographic television channels to his cable service only days after his wife's disappearance. The prosecution stated this meant he knew she would not be returning home. Peterson expressed interest in selling the house he had shared with Laci, and traded in her Land Rover for a Dodge pick-up truck. The only forensic evidence that was offered as a direct connection between Peterson and the homicide was from a single hair, matched through DNA comparison to hair from Laci's hairbrush, that was stuck to pliers found on Peterson's boat. Rick Cheng, a hydrologist with the United States Geological Survey and an expert witness on tides of the San Francisco Bay, testified as a witness for the prosecution. During cross-examination, Cheng admitted that his findings were "probable, not precise." Tidal systems are sufficiently chaotic, and he was unable to develop an exact model of the bodies' disposal and travel. As the trial progressed, the prosecution opened discussion of Peterson's affair with Frey and the contents of their secretly recorded telephone calls. Charles March, a fertility specialist, was expected to be a crucial witness for the defense, one who, according to the San Francisco Chronicle, could single-handedly exonerate Peterson by showing that Laci's fetus died a week after prosecutors claimed. Under cross-examination, March admitted basing his findings on an anecdote from one of Laci's friends that she had taken a home pregnancy test on June 9, 2002. When prosecutors pointed out that no medical records relied on the June 9 date, March became flustered and confused on the stand and asked a prosecutor to cut him "some slack", undermining his credibility. Summing up this key defense witness, Stan Goldman, a criminal law professor at Loyola Law School in Los Angeles said, "There were moments today that reminded me of Chernobyl." According to one newspaper account about March's testimony, "By the end of his testimony Thursday, legal analysts and jurors closed their notebooks, rolled their eyes and snickered when they thought no one was looking". Motive The prosecution presented Peterson's affair with Frey, financial problems, and impending fatherhood as motives for the murder, surmising that he killed Laci due to increasing debt and a desire to be single again. Verdict and