A high school English teacher in Montgomery County is accused of having a sexual relationship with a student.

Sean McCullough is charged with child endangerment, child pornography possession.. and related offenses.

Police say McCullough had a sexual relationship with an underage girl he taught at Methacton High School in Eagleville.

They say the relationship started during the girl's senior year in 2009.

McCullough's relationship with the girl included sexually explicity Facebook communications, emails, exchanging nude photos and inappropriate sexual contact, officials said.

Officials said he admitted to police he had an inappropriate sexual relationship with the girl while she was still a minor.