Cooper's lead attorney told jurors Tuesday that Cary police detectives failed in the basic rules of investigation while trying to find his wife's killer.
Howard Kurtz said investigators did not dispassionately gather and evaluate evidence, and instead fit evidence to their theory that Cooper was the killer.
"They considered rumors, gossip, and hearsay as fact," he said. "Justice was sacrificed on the altar of vengeance."
Cooper is accused of killing his wife Nancy in 2008. She was last seen alive by friends at a neighborhood party in her Cary subdivision the evening of July 11.
Cooper told detectives his wife returned late that night and went out for a run around 7 a.m. the next morning but never returned. Her body was found by a drainage pond in an unfinished subdivision a few miles from her home two days later. The medical examiner said she had been strangled.
Prosecutors allege Brad killed Nancy because he was angry she planned to divorce him and move with their two daughters to Canada.
In his closing argument, prosecutor Boz Zellinger said there are incontrovertible facts in the case. He said Brad Cooper used his computer to Google the location his wife's body was found 12 hours before she was murdered.
He also said Cooper repeatedly lied to police and lied in a sworn deposition.
"Why is the defendant lying about where he was the day before his wife was murdered?" asked Zellinger.
Cooper's lawyers say he is innocent and have characterized the investigation by the Cary Police Department as inept. They say detectives focused on Cooper from the beginning of their investigation and never looked at other suspects.
"The guilty party or parties has remained free," said Kurtz Tuesday in his closing argument.
Kurtz went on to list all the ways he said Cary police mishandled evidence in the case - including erasing data on Nancy Cooper's cell phone.
"It was destroyed intentionally to prevent any information from the Blackberry from getting out," claimed Kurtz.
The defense also tried to undermine the evidence about the Google map search, saying there was clear evidence Cooper's computer was tampered with.
But in his closing, Zellinger scoffed at that theory. He said during the same time period, Cooper also went to secure banking websites where he was required to log in, proving he - and not a hacker - was using the computer.
Much of the testimony in the case centered around a phone call that came from the Cooper home to Brad Cooper's cell phone the morning of July 12.
Cooper told detectives Nancy called him while he was making a run to the grocery store. If the call was real, it proves Nancy was alive when prosecutors say she was already dead.
The defense says Cooper - a phone expert who worked for Cisco - did not have the necessary equipment to make the call.
But prosecutors say he did, and he faked the call.
Zellinger pointed out that Cooper had the expertise to even create a special phone number in France so he could talk to a woman he met there.
"If the defendant can create a phone number out of thin air to talk to a woman in France, you think he can fake a phone call?
The jury has the choice of first-degree murder, second-degree murder, or not guilty.