PINOLE -- Pinole police Chief John Hardester retired Thursday, city officials said.

Hardester, who was hired by the city four years ago, resigned due to health-related issues, according to a letter addressed to Mayor Tim Banuelos and the city council.

"It is with great sadness that I have to inform you that Chief Hardester is leaving us effective today," City Manager Belinda Espinosa wrote in an email dated April 3. "He informed me that he has health issues that are impeding his ability to continue in his position any longer ... John has been a good chief and we will all miss him."

An interim chief has not yet been named, city officials said. The department has roughly 30 full-time employees.

Hardester was hired at the department four years ago as a police commander, city officials said. He then served as interim police chief until he was appointed to chief.

Before that, he spent 26 years with the Alameda County Sheriff's Office.

"I did enjoy my career," said Hardester, who said he's worked in law enforcement for more than three decades. "It's been a long time working for the public and it's time to move on. I'm looking forward to the next chapter."

Staff writer Tom Lochner contributed to this report. Contact Natalie Neysa Alund at 510-293-2469. Follow her at Twitter.com/nataliealund.