News that gay D.C. middle school principal Brian Betts met at least one of the three 18-year-old men charged with his murder through a sexually oriented chat line has prompted activists and police to caution the public about meeting people through such venues.

Gays & Lesbians Opposing Violence and the D.C. police’s Gay & Lesbian Liaison Unit issued e-mail alerts in the past two weeks urging gays and others to take precautions before inviting home someone they meet through an Internet site or telephone chat line.

“Do not invite the person into your home without meeting in a safe, public space,” GLOV said in its May 7 alert. “Get as much personal information as possible, including a real face photo, phone numbers and a home address and try to verify the information.”

Kelly Pickard, a GLOV co-chair, said the group issued its alert after learning of another report by area police that a gay man was attacked near Manassas, Va., by someone he met through a telephone chat line.

Another gay male victim was killed in D.C. in January following a liaison arranged by phone, but authorities haven’t disclosed if the hookup originated from a sex chat line.

Insiders familiar with Internet and phone services linked to sexual hookups say the reported cases are the tip of the iceberg and far more incidents go unreported to police because victims often fear embarrassment and the public disclosure of their sexual orientation.

Police in Prince William County, Va., released a photo May 5 of an unidentified male suspect believed to have robbed at gunpoint a 28-year-old man in Manassas whom he met through a phone chat line.

According to Prince William police, the suspect and a male accomplice arrived by car at a prearranged meeting place with the victim at 2:30 a.m. April 12 in the Manassas area and invited the victim into their car. Police said the two drove the victim to Colton Lane, a dead end street, and escorted him by foot to a location between several nearby townhouses.

One of the two suspects then brandished a gun and forced the victim to turn over cash. The two suspects returned to their car and drove away, leaving the victim shaken but uninjured.

The incident occurred three days before Betts’ body was found in his house in Silver Spring, Md. Police said there were no signs of a forced entry into the home. Investigators said Betts appears to have met at least one of the three men arrested in connection with the murder through a sexually oriented telephone chat line — most likely on the night of the murder.

The three men arrested for the murder were Alante Saunders, whom police said had no fixed address; Sharif Tau Lancaster of Northwest D.C.; and Deonatra Gray of Oxon Hill, Md.

At least one other phone chat line-related murder took place in D.C. on Dec. 27. Police and prosecutors said 29-year-old Anthony Perkins, who was gay, was shot to death in his car by a suspect he met through a phone chat line on the night of the incident. In court papers, prosecutors said a witness told police that 20-year-old Antwan Holcomb boasted about pretending to be gay for the purpose of luring a “faggy” to a place where he could rob him.

The witness told police he overheard Holcomb say he shot Perkins during a scuffle as Holcomb attempted to rob Perkins inside Perkins’ car. Police have charged Holcomb with first-degree murder while armed.

D.C. police also have linked the murder of a gay Maryland man in January to a phone conversation in which 17-year-old William Wren of Southeast D.C. allegedly called the victim and invited him to meet him near the youth’s home. Police have charged Wren with first-degree murder while armed for allegedly shooting and killing Gordon Rivers, 47, inside his car while it was parked on Naylor Road, S.E. during a botched robbery.

Police have so far declined to say how Wren and Rivers met, raising speculation that the two might have met through a phone or Internet chat line.

“The New York City Anti-Violence Project documented 25 [gay-related] pick-up crime incidents in 2009, most of which involved Internet dating sites, including adam4adam and Craigslist,” GLOV says in its May 7 alert. “The types of reported crimes range from theft and drugging to sexual violence and murder.”

The alert says that these and local events “further confirms a trend — both locally and nationwide — that gay men who use these methods to arrange meetings are being targeted for violent crime.”

“While this trend has largely gone unreported by local media, GLOV believes that increased awareness and knowledge among the community is a vital component of keeping people safe.”