TAMPA — Military bases in the United States have become fortresses since the 2001 terrorist attacks, with security stepped up and access limited.

Keeping bad guys out is especially important at MacDill Air Force Base because it is home to two of the nation's premier combat commands — U.S. Special Operations Command and Central Command.

But sometimes, all it takes is a garbage can.

A homeless woman has managed to sneak into MacDill four times since October 2012 and live on the base for days at a time, an arrest affidavit by a MacDill investigator says. In one instance, Suzanne M. Jensen, 50, told authorities she entered MacDill by turning a garbage can upside down and using it to climb a wall.

Jensen was charged last month with four trespassing charges and possession of a stolen military ID. She has not yet been arrested on the charges and is not yet represented by a lawyer.

Jensen has a history of trying to enter military installations. In August 2012, she pleaded guilty to a trespass charge after she was accused of illegally entering Fort Myer in Virginia. She was sentenced to time served.

In 2007, she was charged with two federal trespass counts in North Carolina in a case that was eventually dismissed. Court records are unavailable and it is unclear if she was arrested for entering a military installation. But Jensen's address was listed as general delivery at Fort Bragg, a North Carolina Army base.

According to Jensen's June 26 arrest affidavit:

On Oct. 1, 2012, a retired Air Force officer who hires his boat out for fishing excursions, discovered Jensen on his vessel docked at the MacDill marina. Jensen held the boat's ignition keys. The owner, Barney D. Morris, asked Jensen who had given her permission to be on his boat.

"Jensen told him she was with Intelligence Operations and had just come from the Pentagon, which she claimed had given her permission to board all of the boats," the affidavit says.

Morris tried to detain her, but she jumped into the water and swam away, the affidavit says.

Base security and Tampa police with search dogs and an air unit conducted a six-hour search without finding Jensen. Someone then called security after seeing a soaking wet woman at MacDill's Seascapes restaurant. It was Jensen, who was issued a trespass warning and told to stay away from the base.

On Nov. 18, two base security officers spotted Jensen at a MacDill fitness facility. They asked for Jensen's ID, and she presented a military ID that security forces said had been stolen from another woman at the gym.

Then Jensen "showed officers that she used a trash can she got from softball fields just outside the gate to enter the base," the affidavit says. "She said she flipped the can over and used it as a ladder to get over the wall."

Jensen was cited for re-entering the base after a trespass warning.

On Dec. 17, Jensen was again spotted by a base security officer on patrol. She was hiding behind a vehicle. After a brief foot chase, officers found stolen clothing donated to a base thrift shop in her backpack, the affidavit says.

Jensen was cited for re-entering the base.

On Jan. 4, base security again discovered Jensen on MacDill property. This time, she told officers, she had climbed a wall adjacent to the MacDill Avenue gate.

Jensen told officers that "for about eight days she had been living inside a boat that was on a trailer parked in the base's family Camp area," the affidavit says.

Jensen was again cited for re-entering MacDill.

MacDill officials declined Monday to comment on Jensen's actions, saying the base is working with the U.S. Attorney's Office to investigate the case.

William R. Levesque can be reached at levesque@tampabay.com or (813) 226-3432