LOS ANGELES -- Days away from the start of trial, a former English teacher at Arcadia High School pleaded guilty Friday to committing multiple sex crimes involving a 16-year-old female student in his class.

Phillip Sutliff, 34, pleaded guilty to 17 sex-related felony charges, including sexual intercourse with a person under 18, oral copulation of a person under 18, sodomy of a person under 18, penetration with a foreign object of a person under 18, and sending harmful matter over the internet to seduce a minor, said Deputy District Attorney Philip Wojdak.

Sutliff is expected to be sentenced to 12 years and 8 months in prison Sept. 27.

"Our offer in this case is so high because of the severe breach of trust involved in preying on students he was supposed to be protecting and also because of the hundreds of pages of instant messages show a pattern of manipulation and grooming of her," the prosecutor said.

The charges stem from a relationship Sutliff had with one of his students at the high school from 2004 to 2005. A friend of the girl's family found out about it and notified school officials, who in turn told police, Wojdak said.

Sutliff is alleged to have committed similar crimes with another 16-year- old female while working in Parkson Recreation several years ago, but the charges do not reflect those, Wojdak said.

Wojdak said Sutliff's plea, insofar as it relieves him from going to trial, would "spare him the embarrassment of all this being aired in public ... and save his wife and son a good deal of embarrassment."