A former mental patient who went on a stabbing spree in subways and Manhattan's theater district was convicted Friday of attempted murder and assault.

"They keep saying I'm guilty, but I'm not guilty," Kenny Alexis mumbled as some of the 12 verdicts were read, before the judge had him removed from the courtroom for speaking out.

Alexis, 22, of Boston, was accused of stabbing four people during a 13-hour rampage in June 2006.

A jury convicted him of attempted murder of a Houston man on a subway train and a Brooklyn man on a subway platform. Alexis was acquitted of attempted murder but convicted of assault for knifing two Montreal women in the theater district.

Alexis faces up to 25 years in prison on each attempted murder count. His sentencing was set for March 10.

Defense lawyer Steven Fusfeld argued that his client was mentally ill at the time of the crimes. Alexis had been given a psychiatric examination and found fit for trial, but another psychiatrist testified that Alexis was psychotic at the time of the stabbings and did not realize what he was doing was wrong.

Fusfeld said he would file notice of an appeal, which another lawyer would be appointed to handle.

"I still think there are major problems there," the lawyer said outside court, referring to his client's psychiatric condition.

Prosecutors called Alexis "anti-social and ill-tempered." The Houston man, Christopher McCarthy, testified that Alexis attacked him abruptly as he rode a subway. McCarthy, 24, was stabbed in the heart.