When police arrived, they found the door locked, but could still hear Lee calling for help; "then she went quiet," prosecutor Dafna Yoran told a Manhattan Criminal Court on Monday, per The New York Times.
They then heard another "female" voice telling them: "We don't need the police here — go away."
By the time a specialized unit arrived and broke down the door, Lee was dead in her bathtub naked from the waist up, having suffered more than 40 stab wounds.
Officers say they found Nash hiding under her bed, and one of Lee's own kitchen knives stashed behind a dresser. They said the second voice they heard was Nash, impersonating a woman.
According to investigators, Nash spotted Lee getting out of an Uber on Sunday morning, and slipped into her apartment block behind her unnoticed before the door had closed.
He then followed her up six flights of stairs, keeping one floor below her, until she reached the door of her apartment — when he rushed her, police allege.
As he was led from the scene in handcuffs, he protested his innocence: "I didn't kill anyone,” he insisted. "I don't know what's going on."
Investigators believe the attack was random, and that there was no previous connection between suspect and victim.
Nash was arraigned on charges of murder, burglary and sexually motivated burglary. He was held without bail.
In a cruel twist, it also emerged Nash has a lengthy rap sheet, including assault, possession of drugs and harassment, and was out on bail for burglary when the fatal attack occurred.
One of his previous victims even told the New York Post he recognized the suspect as he was being led away.
"I was watching the news at 5 o'clock, and I seen them taking him out of the apartment and I said, 'That's the guy that f--king hit me!;" David Elliot told the outlet. "He shouldn't have been out on the streets — hell no."
Elliot said he was punched in the face by Nash at Grand Street subway station in September, after the suspect accosted him for swiping his friend in.
"He said, 'If you swipe her in, I’m going to punch you' and I just said, 'Yeah, OK' like I wasn't paying him no attention," Elliot recalled. "[Then] he came out of nowhere and just hit me."
"I used to box. I had four stitches from that punch. I feel he had something in his hand, like, between his knuckles, because for as many years as I boxed, you don't get split like that."
Nash was released on his own recognizance, and was due in court next month for that charge.
In January, he was also charged with criminal mischief and unlawful escape, after police accused him of disabling MetroCard machines at several subway stations, before he attempted to escape the police van after his arrest.
According to the Times, the judge could have set bail for the escape charge in that instance, but didn't as the prosecution never requested it.
Christina Yuna Lee, a graduate of Rutgers University, worked as a creative producer for NY-based online music platform Splice.
"Over the weekend our beloved Christina Lee was senselessly murdered in her home," the company tweeted Monday. "Our hearts are broken."
"Always dedicated to making beautiful and inclusive artwork, Christina is irreplaceable. As we start to process this tragedy, we ask that you remember Christina Lee as the magical person she was, always filled with joy. We wish peace upon her family in their grief."