At 12:30 a.m. Saturday morning, Hayley Carpenter ’11 returned to her Swing Space suite from Thanksgiving break to find that an intruder had moved into her room. Yet despite a buildingwide search, the Yale Police Department was unable to find the trespasser.

Carpenter was with her mother, having just come back from her home in New York, when she entered Swing Space to see vulgarities — “and other juvenile things,” she added — written on the white boards and walls of the third floor.

“At that point I knew something was weird,” she said.

Carpenter had cleaned her common room prior to leaving for break last Wednesday. When she arrived on Saturday, however, the room was in shambles. The refrigerator had been pulled out from the wall and there was food all over the floor.

Upon seeing the mess, Carpenter said she ran to her bedroom to check to see if her other possessions were safe. When she turned the knob, the door would not budge.

She pushed harder. The door opened a crack. And she saw a hand reach out.

“I was shocked,” she said. “I didn’t consider the possibility that someone was in there. I thought it was just furniture blocking the door.”

Carpenter said she screamed out to her mother, who was standing at the entrance to her suite: “Oh my God! Someone’s in my room!”

The two ran down the hallway, away from the room, and called the YPD.

Carpenrter said the YPD arrived within five minutes. Calhoun Master Jonathan Holloway said in an e-mail that the YPD searched the building room by room. But, according to YPD spokesman Lt. Steven Woznyk, the YPD did not find the man.

“Members from the department’s Investigative Services Unit continue to probe the incident in hopes of developing further information,” Woznyk said.

Woznyk said the department was “unable to determine at this time how long the person was actually on the premises,” or how he got into Swing Space.

But Carpenter had a vague idea: she said she forgot to lock her door when she left. Holloway said in an interview that the YPD sweep of the building found more than a dozen suites with unlocked doors.

In an e-mail to Calhoun two hours after the incident, Holloway urged his students to “KEEP YOUR SUITE DOORS LOCKED!”

Luckily, Carpenter said that she did not find anything missing in her suite, and Holloway added that as far as he was aware, no students reported anything stolen. Holloway also said the minor vandalism caused by the trespasser — including “busted” exit signs — can be easily fixed.

In early October last year, a string of burglaries in Silliman and Timothy Dwight Colleges similarly showed no signs of forced entry, which led the YPD to increase its presence in the area. But, unlike summer 2007, which saw 128 instances of Part I crimes — which include both violent crimes and property crimes — there were only 65 instances in the summer of 2008.

There have been fewer notifications of on-campus robberies so far this year than there had been at this time in 2007.