The suspect, Bradley Cooper, claims his wife disappeared when she went out for a jog almost three years ago.
Assistant district attorney Boz Zellinger pointed out items on Jay Ward's Facebook page, including a quote from rock musician Frank Zappa and comments about conspiracy theories as evidence that Ward lacked the ability to adjust privacy settings on his personal social networking account. Ward was called by the defense as a security expert.
"You told the court you're an expert in the field, yet you failed to secure your own network," Zellinger told Ward.
Ward replied that he was not responsible for Facebook security.
"That is not my network," he said. "If Facebook changes its settings, I don't have any control over that."
Ward testified earlier that files on Bradley Cooper's laptop and home computer network could have been accessed by someone. Defense attorneys contend someone may have planted evidence on the computer in an attempt to implicate Cooper in the 2008 strangulation death of his wife, Nancy.
Nancy Cooper, 34, was reported missing July 12, 2008. Her body was found at a neighborhood construction site two days later.
A call from Cooper's home to his cell phone that same morning was presented as defense evidence showing Nancy Cooper was alive at a time investigators contend she was already dead.
Witnesses for the prosecution testified that the phone call could have been faked by Cooper, who was an information technology professional. The prosecution also presented a satellite map found on Brad Cooper's computer showing an image of the site where Nancy Cooper's body was found. Information in the computer showed the image was saved on the computer the day before she disappeared.
Ward told the jury that there was a 27-hour period in which Cary police had custody of the computer and its contents were vulnerable. He demonstrated using a video how free software from the Internet could be used to manipulated information in the computer, saying Cooper's security system was not sufficient to block a determined hacker.
Also called to testify was Chris Wall, an information technologist who befriended the Coopers in 2001. He said he and his wife remained close to the couple until 2005, when Nancy Cooper abruptly informed them she could no longer babysit for their young son.
Prior to December 2005, the two couples socialized frequently, Wall testified.
Wall said he did not see signs of trouble in the Coopers' marriage, but there has been conflicting testimony about their relationship, including that they each had extramarital affairs, and that there were conflicts over money.
Witnesses also said the couple was planning to divorce at the time of Nancy Cooper's disappearance.
Asked about his impressions of Brad Cooper, Wall replied: "Brad was a very laid back guy. I didn't see a lot of anger or excitement out of him. He was always even-keeled."