Investigators said Sunday they may never know why a 19-year-old man dressed in a dark cape and paintball mask went on a shooting rampage in an upscale community, killing two neighbors and himself.

William Freund, described as a loner, used a 12-gauge shotgun (search) Saturday to kill a neighbor and her father, who lived just 100 yards away, police said. Freund then fired into a separate house and aimed his gun at another neighbor before returning home and committing suicide.

"The motive may never be known,"Orange County (search) Sheriff's Department spokesman Jim Amormino said. "It may have been a random thing. What set him off is the big question we're trying to find out."

The victims were identified as Christina Smith, 22, and her father, Vernon Smith, 45.

Police said there was no known link between Freund and the Smiths except that they were neighbors in the large subdivision in the hills above Aliso Viejo (search), a wealthy section of south Orange County.

Amormino said investigators found no evidence that Freund had been using drugs or alcohol, but added that toxicology tests would take several weeks to complete.

Freund lived with his parents and had been unemployed since graduating from high school in 2003, Amormino said.

Police did not know where Freund bought the weapon or whether it was legally purchased. They said his parents told them they had no clue he had been keeping a gun in their house.

The violence occurred Saturday morning when Freund drove the short distance to the Smiths' house. A 20-year-old son escaped after hearing shots.

Freund then walked across the street and fired into another house, where an occupant suffered cuts from broken glass, Amormino said.

Freund tried to fire at a neighbor who came outside after hearing the commotion, but the gun misfired, Amormino said. Freund went home and killed himself with the same firearm.

"It's without a doubt very bizarre behavior," Amormino said.