Nicholas Brooks, whose father was an Oscar-winning composer who wrote "You Light Up My Life," put his face in his hands silently as the murder verdict was read. His girlfriend, Sylvie Cachay, was found partially clothed in an overflowing tub in their rented Manhattan hotel room on Dec. 9, 2010.
Cachay's friends cheered when the verdict was read, and Brooks' sister wept loudly and shook.
Brooks, 27, faces 25 years to life in prison when he's sentenced in August.
Defence attorney Jeffrey Hoffman argued Cachay drowned accidentally, passing out from an overdose of prescription pills she took to treat migraines and fibromyalgia, a disorder that causes widespread pain in the body. He said investigators rushed to arrest Brooks because they needed a suspect in the high-profile killing, which became national news.
He said Cachay, 33, was "under the influence of drugs, partially clothed, to say the least not in a rational state" when she got into the tub.
But prosecutors sought to show that Brooks strangled Cachay because she was breaking up with him. The medical examiner ruled that forcible drowning and strangulation caused her death, in part because of bruising on her neck and burst blood vessels in and around her eyes.
Assistant District Attorney Joel Seidemann said there was obvious tenderness between Brooks and Cachay but their relationship was made up of extreme highs and lows — and Brooks killed her in a low.
"When he held her neck and dunked her underwater ... that was the defining moment," he said.
Brooks and Cachay were introduced by a friend in 2010 but were constantly on-again, off-again. Cachay didn't like that they would drink too much together, her friends testified. She wanted Brooks to get a job and be more proactive about the relationship.
Cachay worked as a designer for Marc Jacobs, Victoria's Secret and Tommy Hilfiger before she opened her own swimsuit line, Syla, in 2006. But the line struggled during the recession and closed two years later.
Brooks was a college dropout who worked odd jobs. Prosecutors said he had a penchant for escorts and marijuana. His father, Joseph Brooks, killed himself in 2011 after he was charged with sexual assault in a casting couch scheme.
On the night of Cachay's death, Nicholas Brooks knocked over a candle and started a small fire at her apartment, burning her hair. So they went to the Soho House, an exclusive hotel and club that cost $1,800 a year and upward for a membership. Surveillance footage shows them checking in at 12:31 a.m. Brooks is then seen pacing the hallway, then going down to the lobby and returning several times before he puts on a coat and leaves at 2:18 a.m. Cachay's body was discovered by hotel staff at 3 a.m.
Brooks later returned, a move Seidemann said was a calculated risk.
"He was not certain that he'd done enough to fool the police," he said.