A PHILADELPHIA JUDGE said Wednesday he was convinced that a disabled, retired Marine was being attacked in the moments before he fatally stabbed a man last October, but he concluded that the stabbing was still a criminal act rather than self-defense.

Common Pleas Judge Benjamin Lerner then convicted Jonathan Lowe, 57, of voluntary manslaughter and possession of an instrument of crime. The judge found him not guilty of the more-serious charges of first- and third-degree murder.

Lowe, who wears a pacemaker and has survived two strokes and two heart surgeries, could face up to 12 1/2 to 25 years in prison when Lerner sentences him Aug. 16.

The case underscores how uncertain the claim of self-defense can be, even in a state that revised its "Castle Doctrine" last year to give an individual the right to use deadly force in self-defense anywhere in which a person has a legal right to be. The revised law also eliminated the duty to retreat before using that force. Lowe's case was featured in March in a Daily News article about the revision of that doctrine.

The voluntary-manslaughter conviction means that Lowe committed the stabbing under provocation but that his actions were unreasonable, or imperfect self-defense, Lerner said.

"There are some unanswered questions in my mind about what happened here," Lerner said. "We will never know exactly how this incident began, and I don't think we will ever know, 100 percent, when the stabbing began."

During the two-day nonjury trial, Lowe and his attorney, Samuel C. Stretton, argued that he acted in self-defense on the evening of Oct. 1, 2011, when he was jumped by Loren Manning Jr., 51, and at least two other men on Cecil B. Moore Avenue near Bouvier Street.

"When he had his hands around my neck, I pulled out my knife and started stabbing him," Lowe testified Wednesday.

Stretton noted that Lowe stayed at the scene and cooperated with police, believing himself to be the victim.

Stretton said case law barred him from introducing Manning's 18 criminal convictions at trial because Lowe wasn't aware of them and most of them were too old, the most recent from 2002. According to court records, Manning was awaiting trial for allegedly knocking out a woman's teeth while robbing her two years ago Thursday.

Assistant D.A. Carolyn Naylor argued this week that Lowe had been the aggressor.

Lowe testified that he used a small, quick-open knife to stab Manning after being knocked to the ground and choked during a robbery attempt.

Two Temple University students said Manning was chasing Lowe and trying to hit him with a metal pole before he caught him. Manning then pinned Lowe to the ground, they said.

But both students said they did not see Lowe stab Manning while the two men were on the ground, nor after Manning got up and quickly collapsed from four stab wounds in his neck, thigh and back.

Naylor seized on inconsistencies between the testimonies of Lowe and the students, including where the stabbing took place. She argued that before the students came upon the struggle, Lowe stabbed Manning from behind before both men ended up on the ground.

She noted that two stab wounds were in Manning's back. She also said Lowe showed intent to kill with malice because after Manning fell mortally wounded, Lowe taunted him and even tried to stab him some more.