HOUSTON -- A Rice University student who has been missing for a month made purchases that suggest his disappearance may have been planned, KPRC Local 2 reported Wednesday.

Matthew Wilson, 20, was last seen at his off-campus apartment on Dec. 15.

Rice University police said Wilson bought a car cover, car window shade, charcoal and matches a few days before he went missing. He also withdrew $500 from an automatic teller machine, officials said.

Police said gasoline was purchased with his debit card shortly before midnight on Dec. 14. The card has not been used since.

Wilson's backpack was missing from his apartment, but his cellular phone was left behind, investigators said.

Detectives said the purchases suggest he may have wanted to protect his car, a silver Dodge Neon with Oklahoma license plate 863 MCZ, from the elements.

Wilson, a junior majoring in computer science, was not known to drink or party. He was reported missing after he did not turn in his final work for his courses.

Wilson is white, 5 feet 7 inches tall, 135 pounds and has red hair, a full beard, green eyes and wears glasses.

A reward of up to $25,000 has been offered for information about Wilson's disappearance. Rice University and Wilson's family have each offered $10,000 for information that leads to his return. Crime Stoppers has offered $5,000 for information that leads to felony charges if any crime was committed.

Wilson's family and friends have started a Web site that they hope will help find him.

Anyone with information about Wilson is asked to call Rice police at 713-348-6000.