A man who prosecutors say shot and killed his cousin over a long-running dispute about a missing ring has been sentenced to 18 years in prison.

The U.S. Attorney's Office said in a news release that 67-year-old Roosevelt Robinson of Washington was sentenced Friday in D.C. Superior Court. He had pleaded guilty to second-degree murder.

According to the government's evidence, on Aug. 21, Robinson confronted his cousin, 63-year-old Loretta Carswell, in front of her home.

Prosecutors say Robinson asked Carswell about a ring he believed she had stolen from him, and she denied knowing anything about it.

Authorities say Robinson pulled out a Ruger .357-caliber Magnum revolver and shot Carswell in her forehead, killing her.