PORTLAND, Maine — The man arrested in connection to the death of 22-year-old Isahak Muse made his first appearance at Cumberland County Superior Court Tuesday morning.

RELATED: Man arrested in connection with murder of Isahak Muse

Portland Police apprehended 24-year-old Mark Cardilli Jr. April 5. 

In the courtroom Tuesday morning Cardilli's lawyer entered a plea of not guilty as he stood beside him. The judge ordered Cardilli be held without bail.

Muse was shot and killed March 16 after an altercation at a home on Milton Street, according to police. 

Police said Cardilli Jr. lives at that address with his family.

RELATED: 'It'll take time,' Portland Police say murder of Isahak Muse is complex while family wants answers now

Cardilli told police he fired the gun into Muse’s chest in self-defense, a medical examiner reported that the fatal bullets hit the victim in the back, according to the Portland Press Herald. 

Mark Cardilli Jr. and Isahak Muse were students at Deering High School at the same time. Cardilli graduated in 2013. 

Isahak Muse and Mark Cardilli Jr.
Portland Press Herald

Cardilli is a former member of the police department's "explorer" program. It allows high school students to learn more about careers in law enforcement.