OMAHA, Neb. (AP) – Authorities searched Thursday for a 13-year-old boy and a female middle school teacher believed to be on the run from central Nebraska after police began investigating whether the pair had an intimate relationship.

Kelsey Peterson, 25, a sixth-grade math teacher and basketball coach at Lexington Middle School, was placed on administrative leave last week. A judge issued an arrest warrant Monday charging her with kidnapping, child abuse and contributing to the delinquency of a minor.

Authorities believed the two were traveling together in Peterson’s car, and police nationwide were notified about them. Court documents said the boy was last seen Oct. 26.

“We’re still focused on locating both of them, whether they’re together or not,” Dawson County Attorney Elizabeth Waterman said Thursday. “I think right now anything is possible.”

The boy, 13-year-old Fernando Rodriguez, was an eighth-grader at the school, but district Superintendent Todd Chessmore said he wasn’t sure whether Peterson was his teacher.

The Associated Press generally does not identify people who may be victims of sex crimes, but the boy’s name has been widely publicized as police search for him.

Court documents showed authorities had recovered several e-mails and letters in which the two professed their affection for one another.

In letters, the boy called Peterson his “Baby Gurl” and said their relationship was “just not about the sex but that it was pretty good,” according to court documents.

Court documents say Peterson’s school-issued laptop contained letters to the student, including one from April saying she loved him, thought he loved her, was “100 percent faithful” to him and would always be faithful.

The boy’s aunt, Laura Rodriguez, told KRVN-AM in Lexington that the family believed Peterson gave the boy a cell phone without his family’s knowledge so she could reach him more easily.

Police said the boy contacted his family over the weekend and said the two were in Grand Island, about 85 miles east of Lexington. Police also said the pair were apparently spotted Friday night at a Denver convenience store, and Sunday in Ogallala, in western Nebraska near the northeast tip of Colorado.

According to court documents, Rodriguez told police that she talked to her nephew by phone, and that he asked her whether a visa or passport was required to travel to Mexico.

Police referred questions Thursday to Waterman, who would not say where police were focusing their search or comment on reports about where the pair were spotted.

Lexington, a farming and meatpacking town of about 10,000, is about 220 miles west of Omaha in central Nebraska.

AP-ES-11-01-07 1829EDT