Jennifer Schorn, chief of the Bucks County District Attorney Office's major crimes division, said Romig made advances to two basketball players he coached at Faith Christian Academy in Sellersville in 2008 and 2009. One was a girl who got a text message from the coach, as she sat next to him on a bus, saying he wanted to have sex with her, Schorn said.
Faith Christian officials learned about the accusations but failed to report them to authorities, according to Schorn.
Instead, they let Romig resign.
In a statement after his arrest last year, Faith Christian said Romig had resigned for health reasons.
Schorn said that such allegations would have warranted criminal investigation, and that Romig could have faced a misdemeanor charge. She also said the school could have been guilty of a summary offense for failing to report the accusations.
Too much time has since elapsed to pursue the case, Schorn said.
The inaction also allowed Romig to get another job.
"Pennridge had no warning," Schorn said after the hearing before County Court Judge Wallace "Skip" Bateman in Doylestown.
E-mails and a phone call to Faith Christian officials were not returned Monday. Romig did not dispute the prosecutor's assertions.
He was charged last fall with the assault of the Pennridge student.
He had coached her since she was 14 and on a travel team, the Sellersville Belles. The sexual relationship with the girl, now 16, began last year and included Romig and the girl exchanging explicit photos and videos of themselves, authorities said.
The girl's parents became suspicious after seeing an increase in text messages in the girl's phone records, prompting them to look through her phone and then call police.
Romig will be sentenced following an evaluation to determine whether he is a sexually violent predator.
Schorn said Romig faces up to 48 years in prison but sentencing guidelines call for far less.
Romig left the courtroom covering his face and ignored a reporter's questions. His attorney, Marc Steinberg, also declined to comment.
Romig remains in the Bucks County prison with bail of $1 million.
"We've been really lucky that he's in custody," Schorn said. "The victim's family had legitimate reason to fear that he would run off with their daughter."
Schorn said that after Romig was arrested, he "professed his love" for the girl in an interview with detectives.
Schorn urged other potential victims to come forward.