LAPD officials confirmed in a statement that detectives spoke to Mayweather on Wednesday, saying only that he was "cooperative" during the interview. The department did not provide any other details, saying the information obtained during the interview "will remain confidential."
But a source familiar with the case said Mayweather told investigators he spoke to Hayes during the incident, and at one point tried to stop the rapper from killing himself. The source requested anonymity, citing the ongoing investigation.
Police went to Hayes' apartment -- in the upscale Park La Brea complex in the city's Fairfax district -- about 7:30 a.m. Monday after a shooting was reported, the LAPD said. When officers arrived, they heard more shots.
A SWAT team entered the apartment and found two people inside who had been shot: Hayes and his wife, Stephanie Moseley, a 30-year-old dancer who appeared on VH1's show "Hit the Floor."
Investigators later determined Hayes killed Moseley, then himself, police said.
Ed Winter, a coroner's spokesman, said Hayes shot himself in the head. Both victims were found in a bathroom, he said.
Mayweather, unbeaten as a professional boxer, is the welterweight world champion.