MIDDLEBURG — A convicted Snyder County sex offender who surrendered to police earlier this month on new charges faces another jail term and lifetime registration on Pennsylvania’s Megan’s Law list if found guilty, probation officers say.

John Garman Shirk, 61, of 25 Pine Ridge Lane, Center Township, was already on the Megan’s Law list when he allegedly molested four girls, ages 5-10, over the past two years.

Despite being identified as a sex offender, he was not under supervision of county probation officials, and the parents of the girls involved still allowed him to be alone with their daughters.

After his probation ended following a 1999 conviction and jail sentence, only friends, relatives and the community could have supervised Shirk, probation officers said.

He has been on the Megan’s Law list for the past 10 years, and his probation ended six years ago.

Shirk was first convicted Feb. 22, 1999. He was sentenced the following April to three to 23 months at the Union County Jail on charges of indecent assault of a victim fewer than 13 years of age, and 24 months of probation for corruption of minors.

He was discharged from probation supervision in March 2003, according to Scott Lizardi, chief probation officer for Union County.

On Oct. 2 of this year, Shirk admitted to police that he took two 5-year-old girls on a tractor ride in a field at 6 p.m. Sept. 27, during which he pulled up their dresses and fondled the youths as they took turns sitting on his lap, according to a criminal complaint.

He also allegedly told state police at Selinsgrove that he fondled the girls in the same way on at least two previous occasions within the past three weeks, and that he had similar contact with two girls who reside in Indiana. Those victims, now ages 9 and 10, visited Shirk every summer for the past three years. The last visit was in July, when he took the girls for a tractor ride and put his hands on their clothing above their genitals while they sat on his lap. He said he did the same thing in 2007 and 2008 when they visited.

Shirk, who is being held at Snyder County Jail on $750,000 bail, faces 10 counts each of indecent assault and corruption of minors, and another 10 counts of indecent assault. A hearing was held on Friday in Middleburg.

If convicted of the new charges, it would be his second conviction for the same offense in fewer than 10 years, requiring him to be listed on Pennsylvania’s Megan’s Law list for life.

Megan’s Law became effective in 1996, and in 2004, information about sex offenders on the list became available to the public through the Internet. Offenders are required to notify state police of any changes in their home or work place addresses.

“After they are off supervision, the only monitoring is knowing where they are,” said Craig Fasold, chief probation officer for Snyder County. If they don’t notify police when they move, it is a felony offense if they are caught, he added.

Levels of supervision of a sex offender are determined by county probation departments, based on a risks and needs assessment, Lizardi said. In intensive cases, he said, offenders meet with an officer once a week. Others may be seen by an officer periodically in their home or somewhere in the community.

Prior to sentencing, a case may be referred to the state’s Sexual Offenders Assessment Board, which determines whether the person is a sexually violent predator.