WHITTIER (CBSLA.com) — Investigators Sunday are still trying to determine the cause of death of a top Whittier College athlete.

READ MORE: First Case Of Omicron Variant Detected In LA County

Alyssa Sialaris, 21, was found dead of unknown causes in her off-campus apartment on Thursday night.

CBS2’s Louisa Hodge said the death is a mystery. The coroner would only say there were no visible signs of trauma.

Friend Brandon Wilcox recalls, “Everybody was calling me that day. We hadn’t heard from her. She hadn’t been at track the past two days, she missed class.”

Wilcox added, “When I went to her house and saw her car, I knew something was wrong.”

Sialaris was a member of both the track-and-field and volleyball teams.

READ MORE: Fake Students Potentially Stealing Millions From Financial Aid

A San Jose native, Sialaris was a senior studying nutrition science and kinesiology.

Foul play is not suspected.

Coach Ali Oliver recruited Sialaris to play volleyball two years ago. “She was one of my closet friends. I spent a lot of time with her outside the gym.” A still stunned Oliver said, “I think everybody is just so shocked. How can someone so healthy, so young … so healthy, so beautiful, how could this happen?”

Sialaris was known for being a prankster and a popular student. She held several school records. Sialaris often wore a purple bandana, to stand out.

At Whittier College, a 100-year-old rock was painted purple in her honor.

MORE NEWS: Dodgers' Justin Turner And Wife Renovate Boyle Heights Boys And Girls Club

Hodge said a vigil was being planned for Sunday night at 8 p.m. — but in keeping in the spirit of her life, and the fact Sialaris was “always late, according to her friends — they expect the vigil to go on about 8:10.