A man with a history of mental problems was charged Monday with killing four immigrants since February, including three apparent victims of misplaced rage from the Sept. 11 terrorist attacks.

The victims were shot at point-blank range without provocation in convenience stores and an all-night laundry. Police say his main motivation was exacting revenge for the terrorist attacks.

Larme Price told a detective that he shot three victims -- one Guyanese, one Indian and one Yemeni -- because he believed each was of Middle Eastern descent, a criminal complaint said. He said he shot a Russian-born man because he "felt bad vibes" about him, the complaint added.

Price, 30, was ordered held without bail following his arraignment on charges of first-degree murder, second-degree attempted murder and criminal possession of a weapon. He was placed on suicide watch at the request of his attorney, John Youngblood.

"Our first concern is for Mr. Price's physical well-being," Youngblood told reporters.

The defendant's relatives refused to comment as they left the courthouse.

The killings began on Feb. 8 with the shooting of John Freddy, 40, a Guyana native drinking coffee at a Queens convenience store as he waited to go to work at a supermarket across the street. A surveillance camera showed a man in a dark coat, baseball cap and hooded sweat shirt shooting Freddy behind the ear.

About two hours later at a Brooklyn store, Indian immigrant Sukhjit Khajala, 50, was fatally shot in the face with the same .40-caliber revolver used in Freddy's killing, authorities said. Police said $169 was taken from the cash register by a man who shot Khajala after a brief conversation, then walked away slowly.

Russian-born laundry manager Albert Kotlyar, 32, was killed March 10. Ten days later, Mohammed Ali Nassir, 54, was shot and killed while sitting near the door of the Stop II Food Market. Another employee was wounded.

Police said Larme, who has two children and a pregnant girlfriend, apparently began having second thoughts about the shootings after reading the Sixth Commandment in the Bible: "Thou shall not kill."

Price's mother, Leatha Price, told reporters that her son struggled with drug abuse and had mental problems that were exacerbated by the Sept. 11, 2001, terrorist attacks. She said she tried unsuccessfully to have him admitted to Woodhull Hospital in Brooklyn.

Woodhull records reportedly show that he was treated at the hospital's Non-Urgent Care Center on March 9 and was released.

Police said they matched a pistol recovered from the home of Price's girlfriend to the shooting of Nassir. They also recovered a baseball cap, hooded sweat shirt and jacket they believe Price wore during the shootings.