A jogger who saved a suicidal teenager from drowning herself in a US lake was a convicted child molester on the run for six years, police said.

Michael Rogers, 49, said he could not bear to walk away and have the girl's death on his conscience, and police in Hamden, Connecticut said an officer involved in the rescue might have died without his help, too.

Rogers was being held without bond, one day after he was arrested at his sister's home on a charge of being a fugitive from justice, police said.

Georgia authorities said they planned to seek his extradition.

Police said Rogers was convicted in 2001 of four counts of child molestation in Georgia but left the state in 2005 against terms of his probation.

Details were not immediately available about the Georgia crime.

Police in Hamden said they first encountered Rogers on September 2 when he pulled the despondent 16-year-old from a murky lake and rescued a police officer who got stuck in deep muck during the rescue.

Rogers, who identified himself to police as Michael Patrick, told the New Haven Register newspaper afterward that he was jogging when he was flagged down by a crying staff member from a child therapy centre who was beseeching the teenager to come back from the lake.

He told the newspaper that he scaled the fence around the lake and restrained the teen for more than five minutes until a police officer arrived and jumped in the deep muck to join the struggle.

Patrick said it was an emotional encounter for everyone, and that the girl was begging him to let her go so she could die.

At one point, police said, Rogers rescued the officer when he became submerged so deep in the muck that he could not pull himself out.

Rogers eventually carried the 16-year-old to shore. The teenager was taken to a hospital and the officer was sent home for the day to tend to bruises and scrapes.

"If I walked away, it would be on my conscience. I just couldn't walk away from that," Rogers told the Register, describing himself as an unemployed security sales consultant from Manhattan who was between jobs and spending time with his sister.

The grateful officer visited Rogers at his sister's home to thank him afterward, and police said he was instrumental in saving the girl's life - and, potentially, that of the officer.

Police learned his true identity on November 23 but did not disclose how they received the information.