I've also seen it reported that it was a homophobic neighbor who called the cops. It was not. It was a lover and roommate of one of the men. They continued their acquaintence after the arrest.
The caller even claimed that he had been assaulted by one of the men (violently and sexually).
He was killed in an assault in 2000 and I can't find any more details on him than that.
Read that link on the men involved in the case for more details.