A fire last month that injured two brothers renting a second-floor duplex unit was set by the homeowner's girlfriend following a lover's spat, according to charges filed Tuesday.

The suspect, Deanna L. Thielbar, and her boyfriend who owned the duplex, Dennis Johnson, lived in the lower unit at 425 Goodrich Av. on St. Paul's West End. A 67-year-old man living in the upstairs unit was rescued by teenager Ricardo Martinez who heard screaming from the building. The man's brother, 65, was later found by firefighters lying unconscious on the floor of the unit. Both men were transported to Regions Hospital for burns and smoke inhalation.

Thielbar, 46, of Pine City, is charged in Ramsey County District Court with one count of first-degree arson for the July 21 fire. She was charged via arrest warrant and is not in custody.

According to the complaint: Johnson told police that Thielbar had been living with him and his grown daughter for two months. Johnson said he and Thielbar argued earlier in the evening of July 20. Johnson went to bed, and Thielbar went for a walk with Johnson's nephew. Thielbar returned home about 9 p.m. and continued arguing with Johnson.

It's unclear what Thielbar and Johnson were arguing about.

Johnson and his nephew left the house and went to a bar. Thielbar was left at the home.

One neighbor told police that she heard Thielbar and Johnson arguing on July 20, and that she saw Thielbar drive away at one point, returning around midnight, the complaint said. The neighbor heard someone "banging around" in the back yard, saw Thielbar walk to the front of the building about 12:10 a.m. and then heard two loud explosions.

"The garage and the house were engulfed in flames, with the fire spreading between the house and the garage," the complaint said. "Thielbar's vehicle was gone."

In an interview with the Star Tribune hours after the fire, Ricardo Martinez, who was 16 at the time, said he and his friends were working on music at a house across the street when they heard screaming. One of the friends looked out a window and saw flames. Martinez phoned for help, put his tank top around his face and climbed onto the roof of the front porch to rescue one of the second-floor tenants.

"As I was going into the house I was thinking, 'What if the floorboards go out? Or it collapses and I get stuck in there?' " Martinez said. "But I still had that thinking that if I don't do something now, he may not make it. So, I just did my best."

When fire crews arrived shortly after 12:30 a.m., Martinez was standing on the porch roof with one tenant. The smoke was too thick inside for Martinez to access the second tenant. Firefighters found the second tenant lying on the floor unconscious.

Johnson tried to force his way inside the building to rescue pets he believe were inside, the complaint said. It's unclear if any pets perished in the fire.

While officers and fire investigators were at the scene interviewing witnesses, Thielbar drove by, the complaint said. A neighbor pointed out her presence, and Thielbar agreed to speak with a fire investigator. Thielbar said she went home to the duplex after work that night, left later with Johnson's nephew and then returned to the home.

Thielbar told the investigator that at some point she realized that Johnson and his nephew were gone, so she drove to Pine City where her parents live, according to the complaint. Thielbar said she stopped in Vadnais Heights, drove by her parents' house in Pine City and returned to the duplex in St. Paul.

Thielbar denied setting the fire, the complaint said. Confronted with the neighbor's eyewitness account of her alleged actions about 12:10 a.m., Thielbar said she lied about driving to Pine City. Thielbar eventually admitted to using her lighter to set a toilet paper roll on fire while she was using the bathroom, the complaint said.

Thielbar also told the investigator that she lit a fire on the back porch on some shelves, according to the charge. She was not arrested, but was admitted to a hospital after making comments about hurting herself and feeling depressed, the complaint said.

In a follow-up interview, Thielbar told authorities that she tried to light the toilet paper on fire but it didn't work, so she lit something on fire in the porch, the complaint said. She said that after lighting the fire, she drove to Johnson's brother's house, turned around and returned to the duplex and pulled around a corner when she saw the fire trucks and panicked.

Thielbar tried to sleep in her car, but was unable to, the complaint said. That's when she drove by the fire again and was stopped by police.

St. Paul fire investigator Jamie Novak determined that one fire started in the first-floor bathroom and another started in the back porch, where the most extensive damage occurred.