HOWELL, Mich. (AP) — The very large dogs were not in special pens or confined in some type of chain-link enclosure on Diane Ruth Cockrell's Livingston County horse farm.

And the small fence surrounding her property about 55 miles northwest of Detroit was not much of a barrier for the purebred and mixed breed American bulldogs she raised.

In the end, there was little to keep four of the 75- to 80-pound pets from crossing Crofoot Road in Iosco Township and attacking 91-year-old Edward Gierlach in his driveway or pouncing on Cheryl Harper 150 feet away, county prosecutor David Morse said.

"It was a wooden fence, almost decorative with three cross bars between posts," said Morse who will attempt to prove the 51-year-old Cockrell was responsible for the fatal Sept. 13 attacks in the quiet, rural community.

The rustic fence was more suited to keep in large animals, like the horses she kept, he said.

Cockrell, who has left her farm and is living with relatives, is expected to surrender to authorities Friday or early next week.

When she does, Morse says she will be arraigned on two counts of a dangerous animal causing death in the attacks on Gierlach and Harper, and one count of allowing dogs to stray.

The first two charges are felonies punishable by up to 15 years in prison. The third is a misdemeanor punishable by up to three months in jail.

"We have to prove that she knew the dogs' propensity for being dangerous," Morse said. "We also have to prove she was grossly negligent in taking action to prevent harm to others."

The listed telephone number for Cockrell's home was not working. It was not known if she has a lawyer, Morse said.

Cockrell raised the animals, but was not a dog breeder, he said.

At the time of the attacks, authorities say she was not home, instead leaving the dogs in the care of a teenage neighbor.

Police learned of the attacks after Gierlach's body was found in his driveway by his son. They soon found Harper's body lying alongside the dirt road. Morse said the 56-year-old lived nearby and either was walking or jogging when she was mauled.

The four dogs believed to be involved in the attack soon were rounded up.

Cockrell, who has been cooperative throughout the investigation, gave permission to have all 10 of her dogs euthanized a few days later, Morse said.