Those details were revealed in a recorded video statement John Katehis made to authorities that a state Supreme Court judge in Brooklyn on Wednesday ruled can be presented in Katehis' murder trial.
Judge Jon Firetog also said a written statement signed by Katehis and a witness who picked him out of a lineup and a photo array can be used at trial.
Defense lawyer Jeffrey Schwartz had sought to have the evidence thrown out, suggesting authorities had "intimidated" Katehis, who was 16 at the time of the March 2009 killing.
The video statement was recorded hours after police arrested Katehis.
George Weber's body was discovered in his Brooklyn apartment after his boss reported him missing. The 47-year-old died of multiple stab wounds, an autopsy found. Weber had been working as a freelancer for ABC News Radio, the national network.
Katehis, now 18, is being held without bail. Jury selection is scheduled to begin Thursday. His lawyers plan to argue Katehis felt threatened and was defending himself when Weber pulled out a knife during the sexual encounter.
In the video, Katehis is seen leaning back in a chair, eating a doughnut, and joking with the prosecutor asking him questions.
Katehis said he came across Weber's Craigslist ad offering to pay someone to smother him. But prosecutor Anna-Sigga Nicolazzi said during the hearing that Katehis placed a Craigslist ad offering sex for money.
Katehis said that after exchanging e-mails and photos they arranged to meet. After arriving at Weber's apartment from school, Katehis said in the video, he finished a root beer and accepted Weber's offer of a Bud Light and cocaine.
Weber demonstrated for Katehis how he wanted the teen to place a cloth sprayed with "poppers" - nitrites inhaled to enhance sexual pleasure - to his face, Katehis said. As Weber lay on a bed, he pulled a small knife from his right pocket, Katehis said.
"The moment I saw the knife - I guess because of the coke - I got super paranoid," Katehis says in the tape. "I grabbed for the knife. We were both struggling over the knife ... I freaked and I grabbed for the knife. He tried to yank back. It jabs him in the neck."
He replaced his blood-soaked jeans and socks with Weber's clothing, he said. Katehis said he took $60 from Weber's pockets.
As he left, closing the apartment door, Katehis remembered hearing Weber.
"He was mumbling," Katehis said.
Katehis said he dumped the knife behind a tree near Weber's apartment.
Nicolazzi contends Katehis intended to kill Weber although she didn't give a motive.
Katehis also faces a charge of criminal possession of a weapon.
