New charges have been filed against a Plano man, weeks after he was indicted in what investigators are calling the most disturbing case involving child sexual exploitation in recent memory.

On Nov. 28, Dan Steffen, 69, was indicted on seven counts surrounding child sex crimes.

Those charges include indecency with a child, sexual assault of a child, possession of child porn, and employing or authorizing the sexual performance of a child.

Plano police filed additional charges, including improper contact with a witness and attempted capital murder by terroristic threat.

Investigators say Steffen threatened to kill someone while incarcerated, but wouldn’t say who or if the two charges are connected.

In August, a homeless man who often stayed with Steffen at his home off Covered Wagon Drive told Plano police he witnessed the 69-year-old make sexual approaches towards a high school student inside his home.

Court documents say investigators contacted that teenager a few days later. The teen went on to tell investigators that he met Steffen at the Gladys Harrington Library when he was just 10 years old.

According to the teen’s conversations with detectives, he visited Steffen frequently over the years. He later admitted that Steffen often asked him to perform sex acts for him.

In some cases, the teen said Steffen would request sex acts whenever he asked for food or money.

The teen also told detectives that he informed his mother about what went on with Steffen, but that she didn’t care and wouldn’t believe him.

Steffen was arrested in September after investigators with Plano police obtained search warrants to enter his home.

In his interview with investigators, the teen told police that Steffen kept a binder filled with child porn called “Dan’s Favorite Pictures.”

At the time of his arrest, investigators charged Steffen with promoting or possessing child porn. Detectives also obtained a briefcase from a P.O. box inside a Plano business that they say belonged to Steffen.

Inside, according to documents, were digital videos and copies of child porn. Some videos involved Steffen—and some photos were believed to have been taken inside his home.

Investigators fear that multiple victims may have been involved and that abuse could have gone on over an extended period of time.

Court documents even say that one photo may have been from 1999. According to records in Dallas County, Steffen was charged with possession of child porn in 1994 but was never convicted.

It’s not clear what Steffen did for a living, but the original victim in the case told police that he was asked to record several radio segments for a station not located in Texas.

Steffen had his first court appearance on Thursday. His attorney, Todd Shapiro, told WFAA that he was given all evidence collected in the case thus far.

He added that it was, “too early to know the future of the case.”

Another court date is scheduled for January.

In the meantime, Plano police are asking the public to contact them if they feel a child has ever had contact with Steffen.