"I was beyond surprised," Scherer said.
When his lawyer, Richard Foxall, asked him why, Scherer said, "I wasn't there on March 7, 2008," which is the night that prosecutor Michael Nieto believes that Scherer killed his parents.
Scherer's father, real estate investor Ernest Scherer Jr., 60, and his mother, Charlene Abendroth, 57, an accounting lecturer at California State University, East Bay, were found dead at their Castlewood Country Club home in Pleasanton on March 14, 2008. They had been beaten and stabbed, and their bodies were decomposing.
Scherer, 32, said his wife made the comment about the video in a phone conversation with him on April 11, 2008, that was secretly recorded by Alameda County sheriff's investigators.
Scherer's wife, Robyn Scherer, who later divorced him, testified last month that investigators showed her a video of a car similar his entering his parents' complex on March 7, 2008.
The video is one of the prosecution's key pieces of evidence in its case against Scherer.
Scherer, who is on the witness stand for the fourth day and is expected to be cross-examined by Nieto later today, said he developed a theory that someone could have fabricated the date on the surveillance video in a bid to get reward money for helping investigators solve the case.
He said he doesn't think his wife was lying when she told him that the driver in the video resembled him because "I believed the video was being fabricated by someone else."
Asked by Foxall if he believes that his wife was being coached by investigators, Scherer said he didn't think about that during the April 11, 2008, phone call but later believed that might be the case.
"The thought crossed my mind," he said.
Scherer is accused of two counts of murder and the special-circumstance allegations of committing multiple murders and murder for financial gain. He could face life in prison without parole if he's convicted.
Nieto alleged in his opening statement that Scherer killed his parents because he faced financial pressure from his gambling debts and the purchase of an expensive home in Brea in Southern California where he lived with his wife and their young son.