S. Randolph Sengel, Alexandria’s longtime commonwealth’s attorney, has announced he will retire and not seek re-election when his term expires in a year.

Sengel, an understated and well-liked top prosecutor, will have served more than 34 years in the office, 16 of them as the elected commonwealth’s attorney.

“I am honored to serve with a skilled, dedicated and professional staff of assistant prosecutors and support personnel,” Sengel said. “We have worked very hard to establish the highest standards of efficiency, fairness and accountability in the prosecution of criminal cases.”

Sengel gave a nod to assistant commonwealth’s attorney Bryan Porter, who he said he would support as a candidate for the top job.