LANCASTER, Calif. -- A math teacher at Pete Knight High School in Palmdale was in custody Wednesday on suspicion of having had sexual intercourse with a 17-year-old student in April 2004, authorities said.

Gregg Donahue, 29, was arrested at his home in the 2000 block of West Avenue H-6 in Lancaster at 11:30 a.m. Tuesday by detectives from the Los Angeles County Sheriff's Department's Special Victims Bureau, said sheriff's Lt. Art Lucas.

Donahue was being held Wednesday at the sheriff's Lancaster Station, with bail set at $20,000, he said.

The arrest stemmed from allegations by a former high school student who reported last Thursday that she had a sexual relationship with Donahue -- a Pete Knight High math teacher and track coach -- in April 2004, he said.

"At the time of their relationship, the victim was 17 years old, and the incidents occurred at Mr. Donahue's residence, not at the school," Lucas said.

On Tuesday morning, "Mr. Donahue was arrested for unlawful sexual intercourse with a minor," he said, adding that Donahue is currently a Pete Knight High employee.

Donahue is scheduled to appear at the Antelope Valley Municipal Court at 8 a.m. Thursday, according to the sheriff's Web site.