A new lawsuit claims the owner of South Florida rental properties hired as his property manager a convicted sex offender who targeted young boys whose families were tenants.

Adam Goldberg, 42, is behind bars on charges including sexual battery on a minor and molestation since his arrest in late 2013.

Attorney Chris Marlowe represents the families of three boys, ages 6, 12 and 14 at the time of the alleged crimes, who claim they were victims of Goldberg, the property manager.

"He raped little boys, he sexually assaulted them after earning their trust," Marlowe said Monday.

Goldberg's charges are related to the alleged abuse of the youngest boy. He's awaiting trial and it's unknown whether he has an attorney.

At a news conference Monday, the parents of some of the boys said Goldberg was always around.

"He seemed like a very nice guy, never would have thought," one mother said.

The new lawsuit isn't against Goldberg; but against Jerome Stern, the man who owns the properties. Marlowe claims Goldberg is a family friend of Stern's who wanted to give him a job when he got out of federal prison after serving five years on child porn charges.

The suit claims negligent hiring and retention against Stern.

Messages and emails from NBC 6 seeking comment from Stern weren't returned Monday.

"Why would you hire a sex offender knowing the property you own, 9 out of 10, is going to have small kids?" one mother asked.

In a deposition, Stern said: "The only thing I knew about him is he had a charge of pornography, I'm not sure what exactly sex offender means here."

"This is not a case where the defendant did an inadequate background check, they knew exactly who they were hiring," Marlowe said.

Marlowe pointed out that Stern's company asked the court to modify Goldberg's probation to allow him to use the Internet. The lawsuit claims Goldberg lured the boys back to a house where he allegedly raped them.

"I would ask him why, why did you do it? Now my child has trust issues, he don't really trust no one," one mother said.

"That's why these suits are being filed, to remind people that just when you thought you've seen it all, you haven't, it can get worse, it does get worse," Marlowe said. "The man who has the keys to your house really might be raping your children."

Miami-Dade Police are investigating the other two alleged cases involving Goldberg.