amber alert
Missing U.S. teen Amy Yu might be in Mexico, according to an Amber Alert. Pictured: A cell phone displays the Amber Alert issued late on Aug. 5, 2013 in Los Angeles, which marked the first time officials have notified the public of a statewide Amber Alert through their phones. Frederic J. Brown/AFP/Getty Images

Amy Yu has been missing since March 5, with authorities believing she is with the middle-aged father of one of her friends. The 16-year-old Pennsylvanian was last seen at a bus stop that Monday morning, with no substantial updates on the case for nearly two weeks.

However, Mexico’s Amber Alert system sent out a tweet Thursday afternoon telling people to be on the lookout for Yu south of the border. The alert also emphasized that Yu is likely with 45-year-old Kevin Esterly, NBC Philadelphia reported.

“From the investigations, it’s determined that she might be traveling in national territory accompanied by ESTERLY, KEVIN MICHAEL,” the Amber Alert read. “We consider the teenager’s integrity is at risk being that she could be a victim of a crime.”

Yu and Esterly were reportedly in a romantic relationship at the time the two went missing. The age of consent in Pennsylvania is 16, but police still issued an arrest warrant for Esterly for unlawfully interfering with the custody of a child.

The two met at church several years ago and developed a close relationship, as Yu was also friends with his daughter. Esterly would post photos of Yu and his daughter on Facebook, and Yu accompanied the Esterly family on vacations.

Esterly was also listed as Yu’s stepfather in school records, unbeknownst to Yu’s mother. That meant Esterly was able to excuse Yu from school, something he did several times between November and February. After Feb. 9, he was instructed not to do that anymore; by Feb. 15, he was told not to go to Yu’s home anymore, either.

The two may be traveling in a 1999 red Honda Accord, according to police. On Monday, Yu’s mother told CBS News that she just wants her daughter to come home.

amber alert
Amy Yu might be in Mexico, according to an Amber Alert. A cellphone displays the Amber Alert issued late on August 5, 2013 in Los Angeles, California, which marked the first time officials have notified the public of a statewide Amber Alert through their cellphones FREDERIC J. BROWN/AFP/Getty Images