What seemed to concern John Jackey Worman most yesterday, as he stood in Delaware County Court to plead guilty to charges of raping children, was how soon he could return to federal prison.

Worman, 42, of Colwyn, was sentenced in August in U.S. District Court to 120 years in a child-pornography case that prosecutors called "horrifying." Yesterday, in cases involving four Delaware County victims - two infants and two girls between 10 and 15 - he entered a negotiated guilty plea to rape, involuntary sexual intercourse, and rape of a child.

He will receive 17 to 35 years when he is sentenced formally in March, said Judge Barry C. Dozor, who agreed to prosecutors' recommendations.

The state sentence will run concurrent to his federal sentence, Dozor said.

County prosecutors have said they decided to pursue charges after the imposing federal sentence as an extra level of insurance that Worman would never be released from prison.

Dressed in red prison scrubs and shackles, and sporting a full, unkempt beard, Worman asked attorneys if he could be transferred from Delaware County prison immediately after sentencing.

"He very much wants to go back to the federal system," said Michael R. Galantino, deputy district attorney. Worman, Galantino said, thought the counseling programs in the federal prison were better able to help him.

Galantino called Worman "calculating and practical." Security in the federal system, he said, is perceived as better than on the county level.

As part of his plea, Worman must comply with all conditions of Megan's Law, which includes a sexual-predator evaluation. That will take about 90 days, Galantino said.

After accepting the plea, Dozor called Worman's actions "appalling, dreadful, and horrendous."

"No judge can sentence you enough," Dozor said. "There is no forgiveness here, only punishment."

Worman was sentenced in August in federal court for manufacturing and possessing child pornography involving what prosecutors called "unspeakable acts" of child exploitation.

In 2006, after one of Worman's young victims came forward, Delaware County and FBI investigators found 1.2 million computerized images of child pornography and 11,000 video clips of Worman as he sexually abused children. One victim was only 6 weeks old.

He abused at least 12 children, many of whom knew him as a surrogate father.

Contact staff writer Mari A. Schaefer at 610-892-9149 or mschaefer@phillynews.com.