John Elway will not face criminal charges related to the death of his friend and agent, Jeff Sperbeck … because the Riverside County Sheriff says they found nothing criminal.

Sheriff Chad Bianco spoke with the local NBC affiliate in Denver recently … and he gave them an update on the investigation — saying it’s straight-up “over.”

Bianco said, “We’ve talked to everyone involved and we found nothing new. There was nothing criminal, it was what we’ve been saying all along that this was a tragic accident.”

As you know … Jeff fell off the back of a golf cart back in April at The Madison Club in La Quinta, CA. He was put on life support while doctors prepared to remove his organs for donation and later passed away. He was 62.

Authorities determined his cause of death as accidental blunt head trauma, and Sheriff Bianco said all the way back in May that he didn’t believe charges would ever come down against Elway.