A 45-year-old man managed to sign a 16-year-old girl out of her Pennsylvania school 10 times in the last few months and now the two are missing, police said.
Kevin Esterly and Amy Yu disappeared from the Lehigh Valley on Monday with cash and some sort of paperwork, according to police.
"They're probably together somewhere," Colonial Regional Police Detective Gary Hammer said.
As of Friday evening, both were still missing, police said. The U.S. Marshal's Office and agents with the FBI are now assisting with the search.
Esterly and Yu apparently had a secret relationship for months, and investigators said Yu may even have gone on family vacations with Esterly. He is married with two children.
According to a warrant issued after the two disappeared, Esterly signed Yu out of school 10 times between Nov. 13 and Feb. 9 without her parents' permission.
Investigators said it now appears that the girl may have added Esterly to her school emergency contact list as a stepfather. That, they said, would have allowed him to remove the girl from school.
"That's when they came to find out that this young lady had added this gentleman, this Kevin Esterly, as a stepfather on school records," Hammer told NBC10.
Police said Yu's mother called Feb. 9 to report Esterly had signed her child out of Lehigh Valley Academy earlier that day.
CEO Susan Mauser did say the school has a procedure for signing out a student that only allows a person on the student's emergency contact list to take the student from school. She said the school is investigating whether that procedure was followed.
"We can confirm that Mr. Esterly was last present on school grounds on February 9, 2018," Mauser said in a statement. "After that date, due to circumstances we cannot disclose pursuant to student privacy constraints, he was prohibited from entering school grounds, and the police were to be notified if he returned."
On Feb. 15, records show police told Esterly to stay away from the teen's home.
Esterly may be driving a 1999 two-door, red Honda Accord with the license plate KLT-0529. Anyone with information about either person's whereabouts should call Allentown police at 610-437-7751 or by dialing 911.