The former Sacred Hearts Academy teacher accused of having sex with a 15-year-old student pleaded guilty in state court Wednesday to seven counts of sexual assault.

William E. Plourde, 55, faces maximum five-year prison terms for each count when he is sentenced in March. But because of possible extended-term and consecutive sentencing, he could face up to 70 years in prison.

One of the seven counts was originally charged as a class A felony, which carries a mandatory 20-year prison term. Under the terms of a plea agreement with the state, Plourde pleaded guilty to a reduced charge.

When Circuit Judge Glenn Kim asked Plourde if anyone or anything was forcing him to plead guilty, Plourde said, "only my conscience."

Honolulu police went to Plourde’s Date Street apartment on Aug. 7 last year after Plourde called 911 and said he wanted to turn himself in. The responding officer said Plourde admitted to having sexual contact with a minor.

Sacred Hearts Academy Head of School Betty White said she had fired Plourde earlier that day after school administrators received and confirmed a claim against him.