After a string of robberies in and around the University of Minnesota campus this school year, students have been inundated with the message from police: Don't walk around campus alone at night.

But the last four crime alerts issued on campus have been for daytime robberies, a shift that police say means the criminals who have plagued the campus this fall with brazen armed robberies and assaults are becoming desperate due to beefed-up security at night.

"The criminals, unfortunately, are changing their tactics," Deputy U Police Chief Chuck Miner said.

Since Aug. 1, about one-third of the robberies reported on or near campus have been between the hours of 7 a.m. and 6 p.m., according to University of Minnesota and Minneapolis police records.

And the robbers are likely to target people even in groups. Of the 21 crime alerts issued this fall for robberies on and around campus, just two were for crimes in which a lone person was robbed at night. The rest were for crimes that occurred during the daytime or against groups of two or more students.

In the most recent daytime crime, a student studying in the Carlson School of Management was confronted by a man at 3:30 p.m. Sunday who claimed to have a gun and demanded his laptop. He took the student's computer, but the student then called out for help and gave chase. The robber dropped the computer and fled, police said.

A video released by campus police shows two suspects entering the Carlson School shortly before the crime. Authorities said they believe one of the men acted as a lookout for the other. Miner said the video has led to a solid tip.

It was the 32nd robbery on or near campus since Aug. 1, with four on campus and the rest in the neighborhoods close by. The police responded with extra patrols, requests to neighboring agencies for help and a "robbery suppression detail" that included an aggressive patrol of pedestrians for suspicious behavior, such as hanging around an ATM. Some of the people arrested as a result of that effort have turned out to have past robbery convictions or warrants, Miner said.

The number of robberies at the U this fall semester was above average for a fall semester, according to records kept by U Chief Greg Hestness. Since 2004, the campus has seen an average of 19 robberies on or near campus between Sept. 1 and Nov. 30. This year that number was 25. Hestness said he's also concerned that in 50 percent of the robberies this year, a gun was used or implied.

In the U robberies, most victims have been targeted for electronics such as cellphones and laptops, backpacks, wallets or purses. The streak of brazen crimes has put the campus on edge, prompting petitions, a legislative hearing last week and increased police patrols.

Security ramping up

The State Patrol, Metro Transit police, the Hennepin County Sheriff's Office and Minneapolis police have all responded in some manner to this fall's crimes at the U, said Pam Wheelock, vice president for university services.

The extra officers are a start, she said, but extra security, surveillance cameras and lighting are coming, too. Wheelock said the university has electronically controlled door locks on 158 buildings on the Minneapolis and St. Paul campuses and plans to do more by the end of the academic year. More surveillance cameras are coming, too, to the fringes of campus, she said.

The crimes this fall are evidence of changes in the neighborhoods near campus, which are more densely populated than before, she said. That, along with the valuable electronics that students carry or are expected to be carrying, has driven some of this year's crime surge, she said. Even as winter break promises to empty out campus after Friday, officials say, they're not expecting any immediate solutions.

"We're not going to lose focus," Wheelock said.