The disappearance of a 22-year-old college student has been deemed suspicious after his vehicle was found sinking early Tuesday in Lake Lillinonah, police said.

Joseph Zahornacky of Shelton, a junior at Manhattanville College in Purchase, N.Y., disappeared Monday night while driving from LaGuardia International Airport to the college, police said.

His 2000 Jeep Cherokee was found abandoned and sinking shortly before dawn Tuesday off a boat launch in Lake Lillinonah, a significant distance from his route back to the college, police said. Bridgewater is in western Connecticut, more than 70 miles northeast of LaGuardia.

Some of Zahornacky's luggage was in the Jeep, but divers searched the lake for hours without finding Zahornacky or anyone else in the frigid water.

Connecticut State Police spokesman Lt. J. Paul Vance said divers returned early Wednesday to the lake, where they were using sonar devices and other equipment.

Investigators were trying to build a timeline of Zahornacky's actions from the moment he stepped off the plane at LaGuardia to the time that his vehicle was discovered, Vance said.

"We still don't know exactly what we have here — if it's a crime, a missing person, or something else. All possibilities are open right now," Vance said Wednesday. "We're examining everything."

Zahornacky's family and state troopers said they have been unable to reach him since Monday night, and that there were no apparent reasons for Zahornacky to be in the Bridgewater area.

"We don't know anyone up there," his brother, Michael Zahornacky IV, said Tuesday. "We don't have any family up there."

Zahornacky flew into LaGuardia on Monday night after visiting Los Angeles, and called his mother and a friend later that night to say he was on the road and within 20 minutes of arriving at the college, police and family members said.

He purchased gasoline in Greenwich and made a purchase at a nearby convenience store, where surveillance cameras recorded him talking with a petite white woman in her 30s with close-cut red hair, police and Zahornacky's family said.

Michael Zahornacky described his brother as a friendly person who might have given the woman a ride. Family members said they did not recognize her.

Police divers searched Lake Lillinonah for hours Tuesday as a state police helicopter helped the search, but found no sign of Zahornacky or any indication of how the Jeep got from Greenwich to the boat launch.

"We're scared to death," his sister, Mary Minnick, said Tuesday. "It just makes no sense."

Zahornacky is described as a white male, 6 feet tall and 190 pounds, with brownish-blond hair and blue eyes. He was last seen wearing a white T-shirt, blue corduroys, a puffy winter coat and black slip-on shoes.