Mark Cardilli Jr., 25, is seen in a Portland courtroom on Monday. Cardilli is accused of fatally shooting 22-year-old Isahak Muse earlier this year at the Cardilli family's Milton Street home. Muse was dating Cardilli's sister. Credit: CBS 13 | WGME

PORTLAND, Maine — In a surprise move, defendant Mark Cardilli Jr. testified Friday at his own murder trial about his involvement in the fatal shooting of his sister’s boyfriend in March. The 25-year-old Army veteran was the final witness in the weeklong trial before attorneys on both sides delivered closing statements.

He recounted the events leading up to the killing of 22-year-old Isahak Muse, the boyfriend of his then 17-year-old sister Chelsey Cardilli.

But before the trial adjourned Friday, one piece of evidence did not line up with Cardilli Jr.’s account that he acted in self-defense when he shot and killed Muse earlier this year at the Cardilli family’s home at 107 Milton St.

“There was no bullet on the ceiling or the wall. There was in the floor,” state prosecutor Leanne Robbin said during her closing statements. ”The shot must have been administered while Muse was bending over or on the floor.”

A bullet defect was found in the floor of the hallway of the home, police and forensics evidence technicians testified earlier in the week. It was one of three bullets that Cardilli fired at Muse, two of which entered his back on the victim’s right side and exited on his left.

The finding contradicts Cardilli’s account that he shot Muse square on — from the front — as Muse repeatedly punched him in the face.

Attempting to prove he acted in self-defense, Cardilli Jr. said that Muse had refused to leave his family’s home after being asked multiple times by his mother — whose memory of the event turned up spotty during her testimony — and father. Mark Cardilli Sr. was scheduled to testify in the case but did not take the stand.

Defense attorney Matt Nichols argued that Muse was “no longer an invitee at that point. He was actually a criminal trespasser.”

In his testimony, Cardilli Jr. said that a quarrel broke out in the kitchen as he and his father tried to physically remove Muse from the house. Cardilli Sr. was locking arms with Muse as the two pushed each other, while Chelsey Cardilli was hitting and scratching all three members of her family in Muse’s defense. Cardilli Jr. left the kitchen to retrieve his pistol — which was in a locked box in his room next to his cellphone. He came back and pointed it at Muse in an attempt to threaten him to leave.

According to Cardilli Jr.’s account, Muse then charged him, punching him in the face “at least 10 times” and pushed him backwards into several rooms before shots were fired.

Nichols said that “it wasn’t just reasonable, it was wise” that Cardilli acted how he did.

But state prosecutors argued it’s illegal under state law to shoot a guest who has overstayed his welcome.

“Isahak was not an intruder, he was an invitee who had overstayed curfew. And you can’t use deadly force against an invitee,” attorney Leanne Robbin said.

In an attempt to establish a credible self-defense charge, Cardilli Jr.’s defense team has repeatedly referred to Muse as bigger and taller than he was listed in the autopsy.

“We’re hearing he’s now 6-feet, 6-foot-1, 175 pounds — when in fact on the day of his death he was 5’9” and 139 pounds” according to the autopsy taken by the state’s medical examiner, Leanne Robbin said.

The defense attempted to stifle the notion that Cardilli Jr.’s act was racially motivated in any way. He denied the statements attributed to him by his sister — who said Monday that Cardilli Jr. had told her that “Muslims were terrorists” among other racist views.

Isahak Muse was a Portland man whose parents were born in Somalia. Like both Cardilli children, he graduated from Deering High School. Many members of Muse’s family and their friends have watched proceedings from inside the courtroom all week.

Cardilli Jr. said Friday that he thought his sister did not approve of him being in the Army, and denied making demeaning remarks about anyone’s race or religion while he was stationed.

“We’re not at war with anyone else but the terrorists,” Cardilli Jr. said Friday.

Superior Court Justice Nancy Mills has taken the case under advisement and will is expected to reach a verdict next week. The defendant has waived his right to a jury.