Prosecutors said Thursday they will not file sexual assault charges against actor Mario Lopez, who appears in the NBC-TV teen comedy “Saved by the Bell,” because of a lack of evidence.Police began investigating Lopez, 19, after an 18-year-old claimed he raped her April 28 after she went to his house to watch movies. Lopez was never arrested. “A physical examination showed a lack of evidence indicating forcible rape and there were statements from witnesses that contradicted some of the woman’s account,” said Deputy District Attorney Peter Longanbach. After the woman appeared on a tabloid TV program, another woman came forward to tell police about an alleged similar incident in 1991, the District Attorney’s office said. The second woman had never reported the alleged assault to police, but she had told counselors, prosecutors said. The woman appeared credible, Longanbach said. But the fact that she had not reported the incident for 18 months, and the lack of physical evidence, prevented the filing of criminal charges, he said. Lopez, who grew up in this San Diego suburb and now lives in a small guesthouse next to his family’s home, denied the charges.