Tyaina Finch told investigators initially that the police officer's yellow Labrador had his service revolver in its mouth, and as she attempted to pull it out, it fired, killing the officer.
But Delaware County District Attorney Jack Whelan said the statements by the 27-year-old Glenolden woman were "inconsistent."
On Tuesday, she was charged with first-degree murder and related crimes and ordered held without bail in the death of Mark Hudson, 26, also of Glenolden.
Whelan described the couple's relationship as "tumultuous" and said officers had been called to the home numerous times for domestic disturbances.
"We believe she acted on this particular day with specific intent to kill [Hudson]," said Whelan. Finch already was being held in jail for allegedly making terroristic threats and other charges.
"We never let go of her as a suspect," said Darby Township Chief Leonard McDevitt. He said only two people were at the home at the time of the shooting.
Hudson had filed a protection-from-abuse order Jan. 30, saying Finch "came at me with a knife and threatened to kill me." She also allegedly struck him in the face and said she would burn down his house.
The order was dismissed Feb. 19 when Hudson failed to appear in court for the hearing.
Investigators are still looking into the couple's domestic history, Whelan said.
On Saturday about 4 p.m., Whelan said, Finch told detectives the two were "playing around" in the master bedroom of Hudson's three-bedroom corner rowhouse in the 600 block of Magnolia Avenue.
According to court records, the two were "smacking" each other when Hudson "grabbed her from the back and pushed her down on the ground." Finch yelled at Hudson to stop.
The dog, named Simba, was getting in the middle of the two of them. As Hudson went to close the window blinds Finch said she saw the dog carrying his service weapon in its mouth. She grabbed the gun and it discharged. She called 911.
On Monday, Whelan said Finch changed her story, telling detectives she wanted to tell the truth. Her statement was taken at Mercy Fitzgerald Hospital, where she was being treated for diabetes, he said.
"This time she tells us a completely different version," said Whelan.
She told detectives that Hudson grabbed her hair and threw her to the ground. She then locked herself in the master bedroom, picked up his service revolver, and threatened to call "his chief." Finch said she came out of the bedroom, and the two began to fight physically. She returned to the bedroom, took the gun, and went into another bedroom.
Hudson approached, and Finch pointed the gun as he advanced, she said.
But Whelan said her story became inconsistent again.
As Hudson approached her, Finch said: " 'Mark, I'm going to call the cops, stop just stop, please just stop.' "
Finch told police Hudson "flinched" at her, his foot came off the ground and "after that he was shot." She did not recall pulling the trigger, she said.
"Babe, I don't think I'm going to make it," Finch said Hudson said.
Hudson later died at Presbyterian Hospital of his injuries. The medical examiner ruled his death a homicide.
"I believe she was using his position as a police officer as a wedge," said Darby Borough Police Chief Robert Smythe. Smythe said he believed Finch had threatened to file a protection-from-abuse order against Hudson. He would have had to surrender his service weapon, which would have threatened his career as a police officer, Smythe said.
Hudson was described as a caring young man who was a rising star in the department.
"We have lost something great in this police department," said Janice Davis, president of the Darby Borough Council.
Services for Hudson have been scheduled tentatively for Saturday in Collingdale.