By Paul Meincke
Evanston, IL (WLS/CNN) - The FBI has joined in the search for a missing Northwestern University student.
Harsha Maddula disappeared over the weekend after attending an off-campus party with friends.
Police say they've interviewed dozens and checked the 18-year-old's cell phone.
Students wanted to help, even though most of them who gathered as local search parties did not know Harsha Maddula, an 18-year-old Northwestern pre-med sophomore and straight-A student.
Maddula disappeared after leaving a party early Saturday morning off campus. He and his friends left at 12:30 a.m., and Madula vanished.
"University police are interviewing all of those students who were at the party," said Alan Cubbage, Vice President of University Relations.
Those interviews have generated no leads.
Maddula's cell phone shows no activity, there's no evidence he used his dorm key, and he doesn't appear on surveillance tape. There are not any clues.
[Reporter]: "You don't have any reason to believe that he would have walked away."
"Oh no, no absolutely not, 200 percent sure. He's not, know reason. He's so excited to help come here," said Dhannalakshmi Maddula, Harsha's mother.
"Excited to help other people. He came one week early to help freshman," said his father, Prasad Maddula.
His parents, who have come in from New York, say their son, a diabetic, would never walk away of his own choosing. He had goals and dreams.
"We just spoke to the President of the University Mr. Shapiro, he assured us he's going ot do everything to find Harsha no matter what," said Prasad.