CLAYTON, Mo. — On the fifth anniversary of Michael Brown’s death in Ferguson, his father urged St. Louis County’s top prosecutor Friday to reopen the investigation into the white police officer who fatally shot the unarmed black 18-year-old.

Before a memorial service in the Ferguson street where a white police officer fatally shot his son on Aug. 9, 2014, Michael Brown Sr. addressed reporters outside of the St. Louis County Justice Center in the St. Louis suburb of Clayton.

“Justice has not been served,” Brown, 41, said as he was flanked by about three dozen supporters. “My son deserved to live a full life. But a coward with a badge … chose not to value his life.

“My son was murdered in cold blood, with no remorse and no medical treatment,” said Brown, who has never accepted the officer’s claim that he had acted in self-defense.

Prosecuting Attorney Wesley Bell, the county’s first black prosecutor, took office in January after his stunning victory over seven-term incumbent Bob McCulloch.

McCulloch drew criticism for his handling of the investigation into the Michael Brown shooting, with detractors accusing him of guiding the grand jury to its decision not to indict the officer, Darren Wilson, which came in November 2014, three months after Brown’s death.

The U.S. Department of Justice under then-President Barack Obama also declined to charge Wilson, who resigned within days of the grand jury decision announcement.

In a statement, Bell would not say whether his office would reopen the case, but he said it “is doing everything (it) can to understand the underlying issues that contributed to the tragic death of Michael Brown.”

Later Friday, a few hundred people gathered for a memorial service on Canfield Drive at the site of the shooting.

Wilson told investigators that he shot Brown — who was 6 feet 4 and weighed 290 pounds — in self-defense. Some people in the Canfield Green apartment complex near the shooting initially claimed that Brown had his hands up in surrender, but the grand jury found no evidence to confirm that.

The shooting led to weeks of protests that included looting and violent confrontations between demonstrators and police officers, many in riot gear and with military-style weapons. Protests escalated again after the grand jury announcement.

Jim Salter is an Associated Press writer.