California and FBI authorities are joining the investigation into the death of a Black man who was found hanging from a tree in California

• State and federal authorities will monitor the investigation into the death of Robert Fuller, a 24-year-old Black man who was found dead hanging from a tree in Palmdale, California.
• Fuller's body was discovered last Wednesday at about 3:40 a.m. near Palmdale City Hall. Local authorities initially said it appeared he died by suicide, but a further investigation into the circumstances of his death is ongoing.
• LA County Medical Examiner Dr. Jonathan Lucas said an autopsy conducted Friday didn't reveal any evidence suggesting "anything other than a suicide," but he said he felt further investigation is warranted.
• Fuller's sister Diamond Alexander told the Los Angeles Times that her brother would not have taken his own life.
• "We just want the truth," Alexander told the Los Angeles Times. "My brother was not suicidal. He was a survivor."

State and federal authorities will join with Los Angeles Sheriff's Department to investigate the death of a Black man who was found dead hanging from a tree in Palmdale, California.

LA County Sheriff Alex Villanueva said during a Monday press conference that he personally called state Attorney General Xavier Becerra and the FBI. The civil rights division of the FBI will monitor the investigation.

Robert Fuller, 24, was found dead last Wednesday around 3:40 a.m. near Palmdale City Hall. Police initially said it appeared Fuller died by suicide, which prompted outcry from the public demanding a full and thorough investigation.

Medical Examiner-Coroner Dr. Jonathan Lucas told reporters Monday that an autopsy was conducted last Friday, saying "initially there wasn't any evidence that lead us to believe there was anything other than a suicide," but he said he felt further investigation was warranted before an official cause-of-death is determined.

"It is a tragic sad death ... we are doing everything we can to find out what happened," Lucas said.

Hundreds marched to the Palmdale City Hall near where Fuller's body was found, with some suggesting Fuller may have been lynched due to the similarity in manner of death. A petition made rounds on Twitter last Friday — and was even shared by Kim Kardashian West — demanding a full and thorough investigation for Fuller.

As of Monday, the petition had gathered more than 270,000 signatures.

"During such a heightened time with the Black Lives Matter movement and the city's quickness to call his death a suicide before any investigation, there is reason to believe that Robert's death was a lynching," the description of the petition read, adding that the Palmdale and the Antelope Valley have a "history of racism and negligence."

"We demand the Los Angeles Sheriff's Department Palmdale Station and the City of Palmdale to conduct a full, thorough investigation into Robert's death," the petition continued. "We demand security footage in Poncitlán Square to be presented and audio of the call placed when his body was found. We demand justice to be served for Robert and his loved ones."

Multiple local and state elected officials called on state AG Becerra to conduct an independent investigation into Fuller's death, including California Sen. Scott Wilk, Assemblyman Tom Lackey, and LA County supervisor Kathryn Barger.

"The attorney general, as the lead attorney and law enforcement official for the state of California, will lend additional expertise and oversight into this important investigation and provide the community with the answers they deserve," Barger told Fox 11.

"It is my hope that our collective efforts will help to support those struggling and grieving surrounding the circumstances of this tragedy."

Fuller's sister Diamond Alexander told the Los Angeles Times that her brother would not have taken his own life.

"This is really crazy to all of us," Alexander told the outlet. "We want to find out the truth on what really happened. Everything they told us is not right. We just want the truth."

"My brother was not suicidal," she added. "He was a survivor."