A man sexually assaulted a 6-year-old boy in a locker room June 14 at the McGaw YMCA, 1000 Grove St., Evanston Police Department announced Wednesday.

The boy was not injured and no semen was found on him, said Deputy Chief Joe Bellino of EPD. EPD is still investigating the assault.

At about 5 p.m. on June 14, the boy told his mother that the man lured him into a bathroom stall and “inappropriately touched” him while he was changing into his swim trunks, Bellino said.

EPD waited two weeks to announce the assault so that police could get more information and avoid traumatizing the boy, he said. Police try to get as much information as they can from child sex assault victims without reminding them too directly of what has happened, he sai

The boy described the man as about six feet tall, black and in his late 20s or early 30s, with thick braided hair pulled back into a pony tail and some tattoos on his arms. He could not identify the man in a police photo lineup, Bellino said. Police detained a man who was at the YMCA when the boy reported the assault, but the boy said he was not the offender.

The YMCA sent letters about the assault to all its 10,350 members on June 23, YMCA spokeswoman and development director Sarah Flax said. An extra staffer now watches the entrance to the locker room where the boy was assaulted, and everybody entering that locker room is required to sign in, she said. Adults not accompanying children now must use another set of locker rooms in the building.

Flax said the YMCA is not secure enough and that she and its other directors want to make security “much more rigorous.” Everybody entering the building is required to show a membership card at the front desk, but “I can guarantee that it (doesn’t happen) every single time,” she said. The YMCA will have to hire more people to before security can be more thoroughly improved, she added.

The boy was examined at an Evanston hospital and was given a “victim-sensitive” interview at the Children’s Advocacy Center in Northbrook, Bellino said.

“The whole concern here with a victim-sensitive interview is not to have the victim have to relive and re-tell the incident again and again,” he said. The interviews are conducted so that the victim only has to be interviewed once, said Mark Parr, executive director of the center. Center staff, police, and Cook County State’s Attorney and Department of Children and Family Services staff attend the interviews. The center interviews about 350 child sexual assault victims from the north and northwest suburbs every year, Parr said.