October 13, 2011, 3:11 p.m. – This article has been edited to reflect that Lydia’s blood alcohol content was 0.016, not 0.16 as originally reported.

By Mary Bess Bolling and Matt Nelson

A Drake University student who died unexpectedly Saturday afternoon had an undiagnosed heart condition that apparently caused her death, her father said Wednesday.

Lydia Clark, 21, had celebrated her birthday the night before with friends, returning home around 3:30 a.m Saturday. Friends told police she awoke about six hours later and was walking around throughout the morning. At 12:30 p.m., however, they found her unresponsive and called an ambulance. It hasn’t been determined whether alcohol was a factor in her death.

Her father, Brad Clark, said the Polk County Medical Examiner’s Office told the family that his daughter had abnormal heart tissue.

“It could have been related to what she had done the night before, or it could have just been a tragic coincidence,” Brad Clark said. “So what we know for sure are those facts. Her blood alcohol was 0.016, she had abnormal heart tissue and she did not die from alcohol poisoning.”

Des Moines Police Sgt. Steve Woody said that the police investigation into Lydia Clark’s death is complete. Medical examiners sent her heart to Mayo Clinic for additional testing, and the final determination on the cause of death may not be made known for several weeks, Brad Clark said.

Lydia Clark, a rhetoric and international relations double major from Meriden, Kan., turned 21 Oct. 6. She was an active member of Alpha Phi Omega service fraternity. She studied at St. Petersburg Polytechnical University in St. Petersburg, Russia.

Joan McAlister, one of Lydia Clark’s academic advisers, described her as fun and insightful, with a little bit of a shy side.

“She was very unique,” McAlister said. “She had a flair for fashion, and she was a little unconventional. … When I first met her, she was wearing these wild, multicolored sneakers.”

Lydia Clark’s public speaking professor, Stacey Treat, said she had a great attitude. In his first class after her death, Treat opened the period with photographs of Lydia at the front of the classroom.

“As far as I’m concerned, Lydia is still part of the class. She’s still present tense in our classroom,” Treat said. “…She didn’t drop this course. That’s not why she’s not here, and I think it’s important that we not pretend that’s the case.”

Brad Clark said his daughter got along with everybody.

“There’s an assignment that you do in some kind of social studies class where you make your circle of friends and you see how they intersect,” he said, his voice breaking. “Lydia was in everybody’s circle of friends.”

President David Maxwell said the university is focusing on providing support for friends, family and the campus. He added that the campus is “suffering from a loss.”

Lydia Clark was the fourth Drake student to die in 18 months. Maxwell said that every death of a student affects the student body and that the university has had “too many incidents of terrible sadness.”

Treat said teachers care a lot more about their students than students realize.

“People your age aren’t supposed to die,” Treat said, directing his comment to students. “It’s always a tragedy, it’s always a shame, and I hope that students just understand more than anything that professors are here as a resource if they need it, like anyone else.”

Lydia Clark’s roommate, junior Kristen Smith, created a Facebook group, RIP Lydia Clark, where friends have posted thoughts and memories. Smith is the editor-in-chief of The Times-Delphic and Matt Moran, a friend of Clark’s, is a copy editor.