Under pressure from a congressman, the Colorado school that stopped a valedictorian from delivering a commencement speech in which he planned to come out as gay has asked outside lawyers to review what happened.

Denver lawyer Barry Arrington, who is representing Twin Peaks Charter Academy board in Longmont, said in a letter to Democratic U.S. Rep. Jared Polis that the school is hiring a law firm to look into the case. Polis had called for an independent investigation after school officials initially announced their probe would be internal and bristled at suggestions they had violated the rights of 18-year-old Evan Young because of his sexual orientation.

Arrington said he hoped the investigation would be completed by early July. Polis told the AP said he was not prejudging the outcome of any probe and had stepped in with the goal of ensuring the school offered a safe learning environment for students.

Young's father, Don Young, said his son wanted to ensure the school was welcoming to all.

"What if next year's valedictorian is gay?" Don Young said. "Let's stop this now and be a safer school."

The events in Longmont, near Boulder, contrast with a decision by a school in the Colorado mountain town of Carbondale to allow its valedictorian to come out in a graduation speech that earned a standing ovation. That valedictorian's principal, expressing concern about the high rates of suicide and other problems encountered by teens labeled as different, praised her courage and said her speech would help all students feel accepted.

In Longmont, Twin Peaks board president Kathy DeMatteo wrote to Polis earlier this week that officials do not "believe that a discussion of a student's sexual orientation — no matter what that sexual orientation happens to be — is a proper matter for a commencement address."

DeMatteo said Evan Young was barred from delivering his speech not because he is gay but because of his "apparent intention to make a mockery" of the ceremony.

Don Young said his son's peers have been accepting of him. But some adults, he said, hear only that his son was coming out as gay, "and they hate that. The high school students see what the intent of his speech was. But adults can't see that."