Fort mitchell, kentucky (ap) -- a woman stabbed to death while possibly trying to steal a pregnant woman's fetus had been carrying an ultrasound picture of someone else's twins and was wearing maternity clothing filled with padding.

Police said 26-year-old sarah brady, who was nine months pregnant, acted in self-defense thursday when she killed katherine smith.

No charges had been filed sunday and commonwealth attorney bill crockett said he hadn't decided whether to present the case to a grand jury.

The attack happened after smith called brady and asked her to come over and pick up a package supposedly delivered to her by mistake.

"she was mentally disturbed," fort mitchell police sgt. Tom loos said of smith. "there is no question about it."

smith, 22, had been falsely telling neighbors for weeks that she was pregnant, and a search of her apartment after her death revealed a full baby nursery, investigators said.

Brady told police she was attacked when she went into smith's first-floor apartment to look at the woman's nursery. Police released details of brady's statement saturday.

"katie reached into her pocket, pulled out this knife that was already open, put it in the overhand thrust position and attacked her with it," loos said. "sarah was able to make it out into the hallway, but katie reached out, grabbed her by the hair, and pulled her back in."

loos said it appears that brady struck smith on the head with an ash tray and then grabbed the knife, stabbing smith three times, including once in the upper chest.

Loos said that when brady ran out of the apartment and flagged down a passing motorist for help, smith removed her maternity underwear stuffed with padding and called 911. Dispatchers kept her on the line until she lost consciousness.

Smith bled to death. Police described brady's wounds as cuts to her hands.

Loos said sunday that as far as he knew brady had not yet delivered, although her due date was reported as friday.

Smith also had an ultrasound picture of unborn twins, and claimed they were her twins from an earlier pregnancy who died at birth, but loos said it was another woman's ultrasound.

She also claimed to have a scar from a caesarean section, but investigators said it was from another surgical procedure.

"she convinced everyone she knew that she had two deliveries, previously, in hospitals and that those babies died at the time of delivery," he said.

"she was clearly obsessed with motherhood," loos said.

A spokeswoman for st. Elizabeth medical center south in edgewood said smith worked there from january 2003 through april 2004. Hospital officials wouldn't say what job she had or why she left after 15 months.

One of her last jobs was as a nanny, a job she lost shortly after thanksgiving, when her employer began to doubt her pregnancy story, loos said.

Several pregnant women have been killed in recent years by attackers who then removed their fetuses, in some cases to pass the children off as their own.

In december, a missouri woman was strangled and her baby was cut from her womb. The baby was later found alive, and a kansas woman was charged with kidnapping resulting in death.

In 2003, a woman was shot to death in oklahoma, allegedly by another woman who then pretended the 6-month-old fetus was her child. That fetus died.