MPs responded to Buck's home on January 7 regarding a person who was not breathing. 55-year-old Timothy Dean was declared dead on his arrival.
The investigation continues, the department said, and investigators are conducting interviews with "people who have volunteered to provide information."
Buck's lawyer Seymour Amster told CNN in January that Dean and Buck had been friends for more than 25 years. Buck was not charged with Dean's death, and Amster said he did not believe that charges would be made in this case.
"Yes, Ed has people he's in touch with and has problems with drugs, he tries to tell them about it Sometimes they bring their problems to their apartment and that's the problem," Amster said at the time ,
He was not the first
Dean was not the first man to die in Buck's house ̵
The Gemmel Moore, 26, was found dead at Buck's home on July 27, 2017. Moore's death has also been classified as an accidental methamphetamine overdose, the Department of Medical Examiner-Coroner's website says.
In this case, the admissible evidence was not sufficient to prove beyond any doubt that Buck was responsible for Moore's death, according to a LA Public Prosecution Fee Worksheet in July 2018.
Moore's mother filed an unlawful death suit Aga inst Buck, 64, allegedly for injecting her son with a lethal dose of crystal methamphetamine.
The lawsuit describes Buck as a wealthy white man who "had a predatory and hurtful system of soliciting black men and watching as they cling to life." Both Moore and Dean were black.
She accuses him of unlawful death, sexual battery and assault and says he was not prosecuted "because he is white and Mr. Moore was black".
In 2017, he donated $ 10,400 to the Getting Stuff Done-PAC, the Democratic Sen. Kyrsten Sinema of Arizona, $ 2,700 to Rep. Ted Lieu of California and $ 1,000 to Republican Jimmy Gomez California, Republican Pete Aguilar of California, Republican Raja Krishnamoorthi of Illinois, and former Senator Joe Donnelly of Indiana.
Sarah Moon and Madeline Holcombe of CNN contributed to this report.