KENNEWICK, Wash. -- The woman accused of stabbing an expectant mother multiple times in the chest and cutting her nearly full-term baby from her womb has been charged.

Twenty-three-year-old Phiengchai Sisouvanh Synhavong of Kennewick was charged with first-degree aggravated murder in the death of 27-year-old Araceli Comancho Gomez, of Pasco.

Court documents state Gomez had her hands and feet bound with yarn and suffered "massive trauma to her stomach area." An autopsy showed she died of the chest wounds. Her body was found early Saturday in a Kennewick park.

District attorney Andy Miller concluded the murder was a premeditated attack and, as a result, charged Synhavong with aggravated murder. She is being held without bail. She is scheduled to be arraigned next week in Benton County -- a delay of a week after Synhavong's defense attorney said she should be represented by someone with death penalty experience. Prosecutors have not said yet whether they will seek the death penalty.

Synhavong is accused of trying to pass the infant boy off as her own in calls made late Friday night to emergency dispatchers.

A spokeswoman for Deaconess Medical Center in Spokane said Wednesday morning the baby remains in critical condition.

According to police documents, Synhavong told dispatchers she had given birth but feared her baby had died. The woman claimed she was near a JC Penney store, but dispatch data indicated the call had been made from Columbia Park Trail.

Police found the suspect sitting in her car next to a baby, who was not breathing. Also found in the car were blood and tissue. When officers took the baby, Synhavong repeatedly asked, "Is my baby OK?" the document said.

Officers said the woman was wearing only a T-shirt without any pants or undergarments, and was holding a part of an umbilical cord in her hand. A "significant amount of blood and pieces of human tissue" were found in the back seat, the documents said.

Synhavong and the baby were taken to Kennewick General Hospital, where medical tests showed she had not recently given birth.

In an interview with KEPR-TV, Synhavong's family members said the woman had recently been claiming she was pregnant. Then on Friday in the hospital, she claimed the baby police had found her with was hers.

Synhavong eventually confessed to the crime at the hospital, family members said.

Upon searching the suspect's purse, police found a pair of mechanic's gloves soaked in blood, as well as a mucus bulb, a box cutter, yarn, a baby bottle and baby socks.

The victim's son said he remembers seeing a woman matching Synhavong's description offer his mom baby clothes, then ask for her address and phone number at a bus stop near his home.

Synhavong's family said she had spoken to her spiritual leader shortly before the alleged murder. She was acting strangely in such a way that made them suspect she may be possessed, they said.

Miller declined to say whether Synhavong had any pre-existing medical conditions or had taken any drugs on the night she was found with the baby.

"If that becomes an issue, it's an issue that the defense attorney may want to pursue. So that's something we wouldn't comment on," he said.

Synhavong is said to be married with a baby, but family members don't know where her husband is at this time.