For at least the third time since last fall, Waltham and Brandeis police have failed to catch a man allegedly seen masturbating by the tennis courts.Michael Vulfovich '07, who plays for the men's varsity tennis team, said he saw a man two weeks ago sitting on the staircase behind the tennis courts masturbating. Vulfovich was preparing to give a tennis lesson to a young boy who is a friend of his family's.

"I was just like, 'that guy is definitely sitting there and jacking off,'" Vulfovich said, adding that luckily the boy hadn't arrived yet.

He immediately and "nonchalantly" called the Waltham Police on his cell phone. However, just as the police cruiser pulled up, the man fled, and the police arrived just in time to see him run away.

This is the third time Vulfovich said he has seen this man, including once when he saw him sitting on the railroad tracks behind the courts. The man shows up every couple months, Vulfovich said.

"I'm sure he's been there a lot more times," Vulfovich said.

Messages left for Detective Sgt. Tim King of the Waltham Police during the holiday weekend were not returned.

Vulfovich told the officers the man is around six feet tall, is in his 30s or 40s and wore tight, gray cross-country running shorts and no shirt.no shirt.

Each time, Vulfovich said he has called the Waltham Police, who show up and either chase the man down the railroad tracks behind the tennis courts or miss him completely.

"The way they keep showing up makes it easy for him to get away," Vulfovich said.

The man escapes by running across the railroad tracks and then running through a nearby cemetery, Vulfovich said.

Chris Hersel (GRAD), a former player and assistant coach, said he saw the man last fall masturbating while he and several other players practiced.

"It was rather disturbing because we were trying to play tennis," Hersel said.

Players on another court called the Brandeis Police, who notified the Waltham Police, he said.

Officers chased the man down the railroad tracks but never caught up with him, Hersel said.

Director of Public Safety Ed Callahan said Waltham officers "checked all pertinent areas," but the man was gone.

Callahan said he personally responded to the situation last fall and campus police stopped someone who fit the suspect's description, though it turned out to be the wrong man.

Ana Katz '08, a player on the women's tennis team, said the man showed up during a team practice last fall.

The man stood against the fence behind the bushes watching them, Katz said.

"I didn't personally see what he was doing, but we saw that his pants were down and that's when we freaked out and told our coach," she said.

Amanda Cuiffo, the former women's coach, left to call campus police, who showed up after the man had run away.

Ben Lamanna, the men's and women's tennis coach who said has never seen the alleged perpetrator, said, "we have crazy fans, I guess.