NEWTON A Passaic County middle school principal was acquitted Thursday of molesting a 13-year-old girl while riding home from a New York Jets game three years ago. Frank T. Mobilio, 47, of Wantage, who works at a Wayne middle school, would have faced up to 61/2 years in prison had he been convicted of criminal sexual contact and child endangerment. As the jury foreman read the second “not guilty” verdict, Mobilio sighed, then began to cry along with his lawyer. “I knew I was innocent from day one,” Mobilio told reporters outside the courtroom. “Very few people believed me. I don’t know why.” Mobilio’s accuser, who is now 16, and her relatives declined comment on the verdict. Assistant Sussex County Prosecutor Francis Koch said he was disappointed. “I feel worse for the two girls,” Koch said, speaking of accuser and a friend, now 13, who testified as a witness. “The little girls are heroes to me.” Last weekend, the alleged victim testified Mobilio touched her thigh several times inside Giants Stadium and twice brushed his arm against her breasts. She said the fondling continued on the way home in the rear of his minivan, where she said Mobilio made her touch him and that she wiped her hand on her jeans. But police lab tests determined Mobilio’s DNA was not on the girl’s pants, law enforcement officers testified. Mobilio, who has been suspended without pay from his job as principal of the George Washington Middle School since his October 2003 arrest, denied that he ever fondled the girl or made her touch him.