YUMA, Ariz. -- A Yuma man is being held on more than $100,000 dollars bond on charges of forgery and sexual conduct with a minor after posing as a high school student, authorities said.

Authorities said 22-year-old Anthony Avalos posed as a high school student and was fraudulently attending Yuma's Kofa High School.

District officials confirmed Avalos attended Kofa High last year on and off for a total of about 4 months. He returned at the start of this school year enrolled as a senior.

Richard Faidley, Ed. D., the associate superintendent for Yuma Unified High School District No. 70 said that last year Avalos showed up to register for school, claiming he was homeless and staying with an aunt in Yuma. Faidley said federal law requires schools to enroll homeless students without any documentation or records, and then request them later.

The criminal investigation into Avalos started Wednesday after he turned in what appeared to be a fake birth certificate so he would be eligible to try out for the Kofa basketball team. School officials noticed the document has spelling errors and other suspicious things and notified the school resource officer.

Yuma police arrested Avalos.

According to court records, Avalos actually graduated from a Florida high school in 2005. Those same records indicate Avalos admitted to making the forged document on his laptop at home so he could play basketball and try to get a scholarship.

Police said Avalos also admitted to having sex with a girl that he knew was under the age of 18.

Students who know Avalos said they noticed he looked older than all the other students but had no idea he was 22 years old. Students called Avalos a key part of last year's Kofa basketball team, which won the region championship.

Fraidley learned early Thursday night that Avalos did indeed play basketball last year, which violated the AIA rules because he never turned in the proper paperwork required to become a student athlete.

Fraidley said he has launched and investigation that could result in discipline for staff of Kofa Athletic Department.

The school could also face sanctions and be stripped of their region title and forced to forfeit any game in which Avalos played.