A serial rapist is on the loose in New Haven.

In a press conference Thursday morning at police headquarters, New Haven Police Department Lieutenant Julie Johnson announced that five sexual assault investigations have been linked together by DNA evidence to the same offender.

“This is not a common occurrence,” New Haven Police Department spokesman Joe Avery said. “A lot of sexual assault is done by people who know each other. This is something of a different nature.”

Johnson, commander of the Special Investigations Unit, detailed the the five events and described the suspect. She also called for information from the public.

“Any information may be helpful in identifying or eliminating potential suspects,” an NHPD press statement released Thursday said.

The Special Investigations Unit is currently investigating the five assaults, which took place between December 2007 and January 2011, with three to 18 months between each reported crime. The incidents took place on Dixwell Avenue and near the Farmington Canal Heritage Trail in either the early morning or late evening hours. The victims were females walking alone, ranging from a teenager to a 28-year-old woman. In three assaults, the suspect was armed with a handgun.

Avery said that the investigation is being run by the sexual assault unit, which is “a well staffed unit … [that] deals with sexual assault every day of the week.”

“There’s not much [information] we can give for sexual assault because of the nature of the crime. It’s very personal,” said Avery.

Yale Police Department Chief Ronnell Higgins alerted Yale campus about the serial rapist in an e-mail around 12:30 a.m. Friday morning.

“While the victims that he has targeted have not been in the vicinity of campus, we would like to take this opportunity to remind you to take extra precautions, especially at night,” Higgins said. “Be aware of your surroundings, and try not to walk alone after dark.”

Avery noted that the last time he could remember, New Haven had a serial rapist “a few years back.” That rapist, which Avery called the East Coast Rapist, was alleged to have committed three sexual assaults near New Haven in addition to committing rapes in other states along the East Coast. DNA also linked those three previous rapes in New Haven to that serial rapist. As of August last year, ABC News reported that the rapist had not yet been identified.

Only media and police officers attended the press conference Thursday. There were no members of the New Haven public at the event.

According to the news release by the New Haven Department of Police Service, the New Haven rape suspect is a light- to medium-complexioned male, between 5’7”-5’11” in height and approximately 170-200 pounds. He was most recently seen wearing a green winter coat and blue jeans.

The most recent related sexual assault occurred on Dixwell Avenue and Hazel Street.