ATHENS, Ga. (AP) — A University of Georgia professor suspected of killing his wife and two other men outside a community theater has a plane ticket to fly to the Netherlands later this week and left behind an empty passport wallet, federal authorities said Monday.

Law enforcement agencies nationwide have been searching for 57-year-old marketing professor George Zinkhan since Saturday's shootings in Athens, about 70 miles east of Atlanta. Classes resumed at the university Monday as police patrolled the campus with assault rifles.

In a federal court affidavit Monday, FBI Special Agent Gregory McClendon said Delta Airlines has confirmed Zinkhan has a ticket to Amsterdam for May 2.

"He may change the date and attempt to leave early," McClendon said in the affidavit.

The affidavit did not say when the ticket was purchased.

Zinkhan has a house in Amsterdam, where he also teaches. The Vrije Universiteit (Free University) confirmed Zinkhan has taught part-time since April 2007, visiting for about six weeks each year.

In a statement, the institution said Zinkhan had been "a peaceful and talented researcher."

McClendon also said authorities have searched Zinkhan's house and office. He has not contacted family, friends or students and his passport is missing.

"No one can account for Zinkhan's whereabouts," McClendon said.

The shooting happened midday Saturday during a reunion picnic for a local theater group outside the Athens Community Theater.

The victims — Zinkhan's wife Marie Bruce, 47; Tom Tanner, 40; and Ben Teague, 63 — were members of Town & Gown Players, which was staging a performance of "Sherlock Holmes: The Final Adventure" at the theater. Two others were hurt by bullet fragments.

Bruce, Zinkhan's wife, had been serving as Town & Gown's president after years of volunteering with the group. Tanner was a Clemson University economist who taught at the Strom Thurmond Institute of Government and Public Affairs in Clemson, S.C. Teague was one of Town & Gown's longest-serving volunteers and was married to a University of Georgia English professor.

Authorities still don't know the motive for the shootings. On Monday, the university announced that he'd been fired.

University officials said they don't believe he is still in the area and the armed patrols were a precaution.

"Based on what we know now, we feel that he is no longer local," University Police Chief Jimmy Williamson said at a morning news conference. "We just don't think he is close by."

Williamson declined to elaborate, and University President Michael Adams said students should continue to stay alert.

"We continue to urge everyone to exercise caution until the suspect is apprehended," Adams said.

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Associated Press Writer Harry R. Weber contributed to this report.