While acts of violence against students on and near campus have raised safety concerns in the Yale community, crime has also been quietly on the rise in areas housing Yale graduate students further from campus.

Students living in the area derisively called “the Graduate Ghetto” — the area north of central campus and around Science Hill which includes Orchard, Ashmun, Bristol, Linden and Whalley streets — have witnessed a rising number of muggings and other crimes committed by young adults, usually riding bikes, over the past six months.

Violence against undergraduates has prompted the Yale Police Department to send e-mails to the Yale community alerting them to the incidents and recommending security measures. But when Tristan Taylor GRD ’09 was robbed at gunpoint near the intersection of Wall and Temple streets at dusk Friday, the only notice was an informal e-mail circulated among graduate students.

Taylor was walking east on Wall Street when he was stopped by two teenage males, one of whom was on a bike, New Haven Police Department spokeswoman Bonnie Winchester said.

“It was a bit of a shock for it to occur on Wall Street, effectively a few meters from the Whitney Humanities Center, relatively early in the evening,” Taylor said.

Yale Police Lt. Michael Patten said the areas in which graduate students have been assaulted are not areas that undergraduates frequent. The only incident perpetrated against a graduate student reported to the entire Yale community — when Theodore DeLong DRA ’07 was shot in the hand in a mugging attempt — occurred near the intersections of Dwight and Kensington streets, near the homes of many undergraduates residing off campus.

Vipan Nikore SOM ’06, the president of the Graduate and Professional Student Senate, said that communication is strained across the different schools because each school acts as its own “Yale College.”

Taylor’s robbery is part of a growing list of crimes in the area. On Sept. 14, Yale Law School Associate Dean Mike Thompson told law students via e-mail that one if their fellow students was assaulted at the corner of Ashmun and Bristol streets in “broad daylight.” According to the e-mail, the perpetrators of the crime were three males, one on a bike and two on foot.

Wei-Tseng Chen LAW ’09, who lives on Linden Street, said he has witnessed at least three violent incidents in his neighborhood. Around 4:30 p.m. earlier this month he said he saw three teenagers, some on bikes, throw rocks at people and passing cars.

“That location used to be a quiet, safe area,” he said. “It’s frightening because I used to bike there. I saw some people get hurt.”

In addition to this incident, Chen said there have been two robberies in his apartment complex, at least one of which involved a gun. He said the lack of formal discussion surrounding the rise in violence is troubling, especially because he felt his neighborhood was safe two years ago. Since the beginning of last summer, however, he said, violence has been on the rise.

“Two years ago you could even go jogging in the evening, but now people stay at home,” he said. “People thought things would get better after the school year started.”

A Yale Law student who said he wished to remain anonymous was mugged on Howe Street by students riding bicycles in late August. He said police told him he was the third victim that night of a group of youths on bikes.

The crimes against graduate students fit a growing trend in and beyond New Haven — groups of youths on bicycles committing robberies and assaults. Bicycles, Patten said, allow youths to travel greater distances more quickly. They are also easier to obtain and bypass rising gas prices.

Perrotti said crime committed by youths on bikes is not unique to the city.

“When I’m at meetings with other chiefs, there is usually a discussion about what is occurring in other jurisdictions,” he said. “I was talking to the Hartford Police Department chief and there are some similar incidents in his area.”

University police have increased their patrols on and near campus in response to the rise in crime. Additionally, Perrotti said winter weather may prevent the use of bicycles in crimes.

“It’s going to be getting colder and more difficult to ride a bike,” he said. “This may stop bike violence in its tracks. We’ll see after winter if this picks up again.”

But Nikore said now that crime is rising, ensuring the safety of students must be a priority.

“This requires a long-term solution, but we need to take all the short term measures that are out there,” he said.

City officials are searching for solutions for the future. Since the beginning of the year, members of the University and city police have met with Mayor John DeStefano Jr. and members of the New Haven Board of Education and the Yale Child Study Center to discuss ways other than policing to address this problem, Perrotti said.

Patten attributed part of the increase in crime to cutbacks in after-school programs. New Haven Public Schools Director of Instruction Charles Warner said the flow of money to fund such programs has diminished in recent years.

“Fewer schools are receiving federal funds,” he said.

While after-school programs play a part in promoting positive youth development, there are several other factors, including family situation, that are important, Warner said.

But Warner said funding cuts cannot completely explain the increase in crime.

“These kids don’t see a need to participate in these kinds of activities,” he said. “What we’re trying to do through the school district and with our various partners, including the New Haven Police Department, is infiltrate these groups and find out what their needs are.”

While similarities exist among the incidents of crime committed in various parts of the city, Patten said police are not yet certain if the perpetrators are members of gangs.

“I’ve been in discussions with the New Haven Police Department and their belief is that these are not organized gangs,” he said. “These are loosely formed groups and their organization is not good.”