Two former camp counselors from Long Island are facing lengthy prison sentences for alleged sex crimes against children.

According to Newsday, David Greenberg, of Selden, admitted in court Thursday that he tied up a 9-year-old boy and sexually abused him while Keith Meyn, of Oakdale, filmed it. The alleged incident happened in fall 2013.

Greenberg said the victim was a family friend and not a camper at Kenwal Day Camp, where Greenberg and Meyn both worked. While in court, the 37-year-old Greenberg also admitted to taking sexually explicit pictures of two campers from Kenwal.

Greenberg was transported to Long Island three weeks ago from North Carolina, where he is already serving up to 35 years for sex and child porn crimes committed there.

Laura Ahearn, of Parents for Megan's Law, says knowing the warning signs can help protect kids from child predators.

"When camp counselors are a little too interested in your children or maybe want to take your children or teens outside of the camp -- those are indicators that something might be wrong," she says.

Greenberg pleaded guilty to first-degree criminal sex act and possessing a sexual performance by a child. He will be sentenced on Oct. 17 and faces 25 years in prison.

Meyn received the maximum sentence of 15 years in prison for use of a child in a sexual performance.