Students who live in the area said they're not surprised.
"One of my neighbors in particular just leaves their door propped open," said graduate student Tina Rende.
Rende said she always locks her apartment, even when she's home. She said she's not sure why others don't take the same precaution.
"I think part of it's a social thing and part of it's just absent-mindedness," Rende said. "Sometimes, especially for younger students, it's not necessarily a priority. It's the first time they're living away from home, in a city, and they don't really understand safety."
Marquette police said they want to give students a reminder about the importance of always locking up their residences before classes begin.
"If you leave your door unsecured and unattended, crimes of opportunity will happen," said Lt. Jill Weisensel, of the Marquette Police Department. "It's something that's easy to prevent."
Weisensel said the door to door visits, in which officers have teamed up with Marquette Student Government representatives to hand out fliers, should also help build relationships with both new and returning students.
"We're out talking to people rather than just using the internet or sending out a text alert or something like that," she said.