Yale Police Department Chief James Perrotti notified the campus by e-mail on Tuesday evening of the robbery of a graduate student on Sunday and a reported acquaintance rape in early December.

The student was robbed of his wallet and cell phone at 10:17 p.m. on Jan. 20 by two males wearing “ski-type masks and dark winter coats,” according to the e-mail. The robbery took place on Canner Street near Saint Ronan Street, which is approximately 1.3 miles away from the corner of Elm and College streets.

YPD spokesman Sgt. Steven Woznyk declined to comment on the robbery because the NHPD responded to the call. City Hall Spokeswoman Jessica Mayorga could not be reached for comment Tuesday evening.

Perrotti’s e-mail also included mention of an on-campus acquaintance rape that was reported to University officials in early December.

“While no formal criminal complaint has been filed, this is a very serious matter,” Perrotti wrote. “I urge all members of the university community to exercise care in social settings especially where alcohol might be involved.”

Perrotti last informed students of an “off-campus acquaintance rape” late last September. No formal criminal complaint was filed in the September incident.

Acquaintance rapes — in which the survivor knows the offender — account for roughly 84 percent of all rapes. At the end of Tuesday’s e-mail, Perrotti directed students to resources available to them if they are raped, including the YPD and the Sexual Harassment and Assault Resources & Education center.

Tuesday’s e-mail is the first from Perrotti in 2008. He last e-mailed the Yale community in mid-December about a mugging and a purse snatching near campus.

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The New Haven Police Department made a burglary arrest Monday on Hillhouse Avenue, where several Yale classroom and administrative buildings are located, according to a city press release.

Francis Casper, 38, was charged with burglary in the third degree and possession of burglary tools and criminal attempt larceny in the sixth degree after he broke into St. Mary’s Church at 5 Hillhouse Avenue.

The NHPD was dispatched to the scene when the church’s alarm system was triggered. Officers arrived to find Casper leaving out the church’s front door.

St. Mary’s Church is located between Mason Laboratory and Warner House.