updated 10/14 – 2:47 p.m.

KELLER (CBSDFW.COM) – It was first believed to be a deadly home invasion, then it was called a suicide, but police in Keller now say they’re investigating the suspicious death, of a husband and father as a murder.

The Tarrant County Medical Examiner ruled Friday afternoon the man, 40-year-old Gregory Williams, died of a gunshot wound to the head, specifically at the hand of another person.  They ruled the case a homicide.

Keller Police say there is one person who knows exactly what happened Thursday morning in the 1400 block of Jacob Avenue, but her story keeps changing.

The shooting happened at a house inside the gated-community of Twins Lakes.

Yellow taped surrounded the house as police collected evidence and processed the scene. Investigators say Michelle Williams made a hysterical call to Keller police around 4:40 Thursday morning and claimed a man came into the house, shot her husband and hit her in the head.

When officers arrived they found Gregory Williams in bed with a single gunshot wound to the head and a woman with a bruise on her head. What officers didn’t find was any evidence of forced entry.

Authorities from Keller, Colleyville and Bedford responded to the incident, and a police canine unit was brought in to help in the search. But that dog found no indication that anyone else had been in the house

After questioning Michelle Williams, police say her story continued to change, claiming her husband committed suicide.

“She is saying she was in the living room and heard a noise and went into the bedroom and found her husband with a self-inflicted gunshot wound to the head,” explained Lt. Brenda Slovak, with the Keller Police Department.

Authorities say Williams later admitted cleaning up some of the evidence, making pry marks on the door, hitting herself in the face and moving the gun.

“She said her story changed because she did not want her 4-year-old daughter to know her dad killed himself,” Lt. Slovak said.

Officials are calling Michelle Williams a “person of interest” in the case, but have not made any arrests.

Lt. Slovak said the designation is routine. “Anybody that is there when a death occurs is always a person of interest. She was the only person who was there. She knows what happened.”

The couple’s 4-year-old daughter was in the house when everything happened. Police say she was asleep on the couch. The child is now in the care of relatives.