An El Sobrante man was charged this week with sexually assaulting an unconscious woman last year near the Golden Gate Fields racetrack where he worked, authorities report.

On Monday, the Alameda County district attorney’s office charged Ari Herbertson, 28, with the sexual penetration of an unconscious victim, sexual penetration by a foreign object, assault with intent to commit a sex crime and sexual battery by restraint. All four of the charges are felonies. The incident took place in January 2019, police said.

Berkeley Police spokesman Officer Byron White said detectives have been working on the investigation for months, serving search warrants and interviewing witnesses to reconstruct events. Police were able to link Herbertson to the case with DNA, he said.

BPD first learned about the incident last year when a woman said she had been sexually assaulted after leaving the Golden Gate Fields racetrack at 1100 Eastshore Highway. White said police believe the assault took place in the vicinity of the track.

“During the course of this lengthy investigation, detectives developed a suspect and obtained his DNA,” White said in a prepared statement. “After receiving a DNA match for the suspect, detectives submitted the case to the District Attorney’s Office for review.”

Police arrested Herbertson at Golden Gate Fields on Tuesday morning, White said.

Herbertson worked as a horse trainer at the racetrack, he said.

Golden Gate Fields general manager David Duggan told Berkeleyside just after publication that trainers are employed by horse owners, not the track itself. He said the California Horse Racing Board would be the body to determine whether a licensed trainer or other worker would have access to a particular facility.

Duggan said Golden Gate Fields has “a very strong working relationship” with police in Berkeley and Albany, as well as a robust security team that would cooperate with authorities in any circumstance where that was appropriate.

“We take the safety and security of everybody who uses our facility seriously,” Duggan said.

According to Alameda County court records online, Herbertson is scheduled for arraignment Friday at Wiley Manual Courthouse in Oakland.

He is no longer in custody. The amount he posted for bail was not listed in records online as of publication time.

Emilie Raguso (former senior editor, news) joined Berkeleyside in 2012 and covered politics, public safety and development until her departure in 2022. In 2017, Emilie was named Journalist...