Police found Butler suffering from multiple gunshot wounds to the chest inside a home in the 2300 block of Ainger Place SE after responding to a report of a shooting at about 8:30 p.m., according to a police report and officials.
Medics took Butler to a hospital, where he died.
The task force also arrested 49-year-old John Fenner, of Northeast Washington, who was wanted for a charge of first-degree murder while armed (premeditated) in the death of a Southeast Washington man on May 18, police said.
Officers responding to the 100 block of T Street NE for the report of a shooting about 5:30 p.m. located Jonathan Hernandez, 25, face down and unconscious behind McKinley Technology High School, a police report said.
Hernandez was taken to a hospital, where he was later pronounced dead, officials said.
A second man was wounded in the shoulder but survived the attack, police said. Police found at least four vehicles that were damaged by gunfire, the police report said.
Authorities released no details about the charges in either arrest warrant.