Durham, N.C. — Durham and Duke University police will increase patrols near campus, the university said Monday in light of three off-campus crimes over the weekend involving students and an employee.

"The Duke Police Department is extremely concerned about the type and frequencies of crimes that the Duke community has experienced," Aaron Graves, associate vice president for campus safety and security, said Monday in a news release.

At about 7 p.m. Sunday, according to authorities, man robbed a graduate student who was walking north of campus near Poplar Manor Apartments on Louise Circle. The thief took a wallet, cellular phone and iPod.

Police believe the same thief used a gun to rob a Duke employee and his wife who were walking to their apartment at a nearby apartment complex around 10 p.m. The robber took the Duke employee's wallet.

There were no reports of injuries.

And on Friday, Abhijit Mahato, 29, a Ph.D. engineering candidate from India, was found shot to death inside his home at the Anderson Apartments.

Police have not named a suspect or established a motive in his death, and they do not know whether the robberies are related to the homicide.

"It's scary," Duke student Sarah Marshall said. "I hope that they make it safer and put cops out there and do whatever it takes, because I just don't want anything to happen to any other students."

Including the weekend crimes, five Duke students and employees have been crime victims in the past six weeks.

And since January, according to Durham police, there have been 30 robberies targeting Hispanics – including 11 over the weekend – in the area surrounding Duke. Although police have not said whether those crimes could be related, university officials say that what happens in the city affects the university.

That's why university officials also met Monday to review on- and off-campus safety measures, discuss how to respond to recent events and how to help prevent future crimes.

One tactic is e-mail alerts.

"It our effort to give people information, so they can help make decisions and judgments as they go about their daily lives to be aware that this has happened," Graves said. "Hopefully, they can take measures and make judgments that help make them safer."

"People have to be careful." Marshall said. "But you can only be so careful to prevent someone with a gun from going after you."

Authorities describe the assailant in Sunday's robberies as a black man, standing 5 feet 8 inches and wearing black coat with brown fur trim, black pants and white sneakers. He also had on a black or black-and-white bandanna.

Anyone with information about the robberies or Mahato's death should call Duke Police at 919-684-2444 or Durham Crime Stoppers at 919-683-1200. Crime Stoppers pays cash rewards for information leading to arrests in felony cases, and callers never have to identify themselves.