TULSA — Prosecutors filed 28 felony counts against the former operator of a Broken Arrow skating rink accused of sexually abusing 19 boys who ranged in age from 8 to 14 years old.

David Abston, who is scheduled to be sentenced July 31 for his conviction of federal child pornography crimes, now faces 22 counts of sexually abusing a minor child, one count of forcible sodomy and five counts of possessing child pornography.

The state charges filed Wednesday against the former Muskogee police officer stem from an ongoing investigation that began Nov. 8 after federal agents executed a search of Abston’s Tulsa home. During that search, FBI agents allegedly discovered sexual devices, lubricants and condoms in a bedroom occupied by a 10-year-old boy and a computer that contained hundreds of pornographic images and videos.

Since then, investigators with the Tulsa Police Department’s Child Crisis Unit have interviewed several dozen boys who claim to have had contact with Abston. As a result of those interviews, investigators have concluded “that during the past 35 years, the defendant has had several boys living at his residence that he portrayed as his own son. These boys usually stayed with the defendant for three or four years before moving and being replaced by a younger child.”

District Attorney Tim Harris described the “ongoing criminal child abuse investigation as the most extensive ever presented to the Tulsa County district attorney.”

An affidavit filed with the case summarizes statements the boys gave to police and documents evidence found by investigators during subsequent searches of Abston’s Tulsa home. Details in the affidavit reveal a bizarre pattern of sexual exploitation.

Some of Abston’s alleged victims told police they were instructed to take showers and change into boxer shorts provided by Abston. Others were allowed to watch sexually explicit movies and instructed to masturbate.

Others who were interviewed by police said Abston would tell them a woman would be coming over to pleasure them with oral sex. Most of those boys said Abston would then take them into a bedroom, blindfold them and perform the oral sex himself.

While details contained in the affidavit appear consistent from one alleged victim to the next, Abston’s lawyer, Keith Ward, expressed doubts about the validity of the statements. Ward said his client has repeatedly denied the allegations and will plead not guilty to the charges.

“I’m convinced there is no basis to the charges,” Ward said. “These are just allegations (and) I’m hopeful that we’ll draw a judge that will give us a fair trial and we can test the charges in a courtroom rather than a public forum.”

Abston, who turns 56 today, has been held in the Tulsa Jail since Jan. 18 in connection with the federal pornography charges. He pleaded guilty in March to charges of putting images of child pornography on the Internet for distribution and possessing video files of children engaged in sexually explicit conduct.