Braintree Police Chief Russell Jenkins will retire Oct. 7 as head of the troubled department, which has been rocked by revelations that guns, drugs, and cash vanished from the evidence room, according to an announcement from the town. “It has been an honor and a privilege to serve as Chief of the Braintree Police Department these last four years,” said Jenkins, in a letter to the mayor. The department has come under fire after an audit revealed that more than $400,000 in cash, between 60 and 70 guns, and thousands of drug samples, had gone missing from the evidence room....