A 22-year-old man has been arrested in connection with three apparently random shooting deaths in a New Orleans suburb, and ballistics evidence connects him to a fourth death inside the city limits, a Louisiana sheriff said Wednesday.

Sean Barrette of Metairie was arrested late Tuesday and faces charges including second-degree murder in connection with a shooting death late Monday at a Metairie intersection, and two counts of first-degree murder in two fatal shootings Tuesday afternoon near another Metairie intersection. He is also linked by ballistic evidence to a June 6 shooting death in eastern New Orleans and another shooting on June 5 in New Orleans in which nobody was injured, Lopinto said.

"We've not been able to identify any connection between the victims and the suspect," Lopinto said at a news conference. "I believe that he was actually picking his targets at random, shooting them in the vehicle."

A cellphone found at the scene of Monday's shooting was eventually traced to Barrette, said Lopinto. He added that Barrette has had "a history of mental problems," including two commitments for treatment, in December and April.

The victim in Monday's shooting was identified as Isai Cadalzo, 22. Killed Tuesday were Manuel Caronia 45, and Nicky Roseau, 57.

Lopinto had little information about the New Orleans slaying, but New Orleans media report the only shooting death reported June 6 was that of 61-year-old Bruce Reed, found fatally wounded in a grassy area next to a major eastern New Orleans street.

Barrette was arrested without incident at his parents' home. The weapon believed used in the killings has been recovered, Lopinto said.

Lopinto was asked whether race was considered a factor in any of the deaths. Barrette is white. In Jefferson, two of the victims were Hispanic and one was white. The New Orleans victim was black.

There has been no evidence so far to indicate race might have been a motive, Lopinto said. "That could change, obviously, when we continue our investigation," he said, adding that the probe would include scrutiny of Barrette's web searches.