Ammar Harris, 26, a self-described pimp, was jailed pending an extradition hearing Monday in Los Angeles Superior Court.
A neighbor, Gail Gaghagen, said she thinks she saw Harris on Tuesday sitting alone in the gym at Archview Luxury Apartments in Los Angeles' Studio City neighborhood, dressed in shorts and a tank top.
"I just walked by and there was a glass door," she told The Associated Press. "I just I looked at him and he looked at me and that was it."
Gaghagen said she told the same story to FBI agents she met in the apartment elevator after Harris surrendered Thursday. A woman in the apartment was being questioned but wasn't charged with a crime.
The arrest of Harris, a convicted felon in South Carolina who shows fists full of money on Internet posts and boasts of a high-rolling lifestyle with prostitutes in Miami and Las Vegas, ended a manhunt that began after a Feb. 21 shooting and spectacular, fiery accident that killed three people and injured five at an intersection home to the Bellagio, Bally's, Flamingo and Caesars Palace casino resorts.
"I hope anyone out there watching understands clearly if you live in this city, if you work in this city, or you visit this city and act like this person, we will find you, we will prosecute you, and we will send you to prison," Clark County Sheriff Douglas Gillespie said Thursday in Las Vegas.
Court documents allege Harris was driving his black Range Rover SUV when he fired at least five shots into a Maserati sports car, killing Kenneth Wayne Cherry Jr., a rapper who called himself Kenny Clutch.
A passenger in the Maserati, identified as Freddy Walters, was wounded in the arm.
Harris and Cherry had argued minutes earlier in the valet area of the glassy Aria resort, after a night featuring Morocco-born rapper French Montana at the hotel nightclub Haze, authorities said.
The Maserati, with Cherry mortally wounded at the wheel, slammed into a taxi that burst into flames. The cabbie, Michael Boldon, and passenger, Sandra Sutton-Wasmund, of Maple Valley, Wash., were killed.
Two days later, police found the SUV parked at an apartment complex two blocks east of the crash scene.
Lt. Ray Steiber, who headed the investigation, said Thursday that investigators learned that Harris left Las Vegas "pretty rapidly." Detectives fielded hundreds of tips and reviewed surveillance images of the disagreement between Harris and Cherry, collected bullet casings, listened to audio recordings from nearby taxis of the gunshots and obtained traffic camera video of the Maserati speeding through the Las Vegas Boulevard intersection at Flamingo Road.
The day after the shooting, prosecutors obtained a warrant for Harris' arrest on three murder counts, one attempted murder count and several shooting charges.
Las Vegas police said Thursday they had located and talked with all three women who were in the SUV with Harris at the time, including Tineesha Lashun Howard, 22, of Miami. None of them was charged with a crime, Capt. Chris Jones said.
Steiber called the discovery that Howard, who has a history of prostitution arrests, left Los Angeles on Wednesday on an eastbound bus "one of the factors" that led investigators to find Harris in Studio City. Police have not said where Howard was found.
As police in Los Angeles searched the Studio City apartment, Steiber noted that the investigation was not finished.
"We have captured Ammar Harris," the police lieutenant said. "This is an open and ongoing investigation. This is not closed."
Clark County District Attorney Steve Wolfson said Thursday that anyone who helped Harris elude police for a week could still face criminal charges.
Ritter reported from Las Vegas.