HOUSTON -- He hasn't been seen for nearly a week and the family of missing Rice University student Matthew Wilson is desperate for answers, KPRC Local 2 reported Friday.

"This is on my mind. I'm thinking about it all the time," said Wilson's mother Cathy Wilson. "I'm trying to solve it in my head."

The 20-year-old junior was last seen Friday night by his roommate at their off-campus apartment.

Since then, university police say have received several clues including a several-hundred dollar bank withdrawal from Wilson's account.

"But it was taken out the day before the day he was missing and so we don't really know what's going on," said Rice University Police Chief Bill Taylor.

Friday, police announced that Harris County Crime Stoppers is offering a $5,000 reward for information that leads to an arrest and prosecution of a suspect, in case a crime has been committed.

Wilson's landlord, Susan Stubbs, has been in contact with the student's family. She told Local 2 that the family doesn't feel that leads are coming in fast enough. Stubbs said the family went looking for outside help.

"The family had hired a private investigator and according to Kelly, Matthew's sister, Rice Police told her that this detective was getting in their way, so the grandmother fired the detective," said Stubbs.

Rice police chief Chief Bill Taylor told Local 2 that it's been more than 10 years since his police force handled a missing person case. In that incident, Taylor said the student needed to get away but eventually returned unharmed.

Taylor insisted his investigators are doing all that they can to find the diligent, straight A student who never showed up to turn in his finals.

"The reality is that we probably put a lot more energy into this than what most other law enforcement would be able to do because they normally investigate crimes," said Taylor. "This isn't a crime at this point."

If he did leave on his own and is still out there, Wilson's mother is making this plea.

"Try all you can to get home to me," said Wilson trying to hold back tears. "You mean the world to me and you know you do. I love you with all my heart."

Police say Wilson is 5 feet 7 inches tall, 135 pounds, with green eyes, red hair, and a full beard.

If you can help investigators, call Rice police or Crime Stoppers at 713-222-TIPS.