An adjunct math professor at Chestnut Hill College in the Philadelphia area jumped Wednesday headfirst to his death.

Philadelphia police said Rudolf Alexandrov, 71-years old, had a history of depression and suicidal thoughts and had mentioned harming himself in the past. They are ruling his death a suicide. Mr. Alexandrov's wife, Olga, 56, is also an adjunct professor at the college.

Contradicting earlier account that his jump had been witnessed by students and his wife, CBS News later reported that it was unclear who saw the man jump -- 20 to 30 feet to his death -- from the second-floor railing overlooking a veranda inside St. Joseph's Hall. Witnesses said onlookers tried to talk him out of it.

"In no way did any member of his class witness this nor did his wife," said college spokeswoman Kathleen M. Spigelmyer. "To the best of our knowledge, there were only four witnesses at the second-floor level."

The incident occured around 5:30 p.m., before the professor's math class was to begin, reports said.

In a statement, the college said, "We offer our prayers and condolences to all Alexandrov family members and friends at this time of great sorrow."