Woman who 'faked a pregnancy, murdered a new mom and kidnapped her one-week-old baby' says she was promised the infant but the victim changed her mind.

The woman accused of killing a Kansas woman and stealing her baby says in a jailhouse interview that the woman had agreed to give her the child but backed out of the deal at the last moment.

In a television interview in Spanish, Yesenia Sesmas told KUVN-TV of Dallas-Fort Worth that Laura Abarca-Nogueda had agreed to turn over her newborn daughter to her but reneged on the agreement.

In the interview in the Dallas County jail, the 34-year-old Dallas woman admitted that she killed Abarca-Nogueda but said she did not mean to. 

She said she threatened Abarca-Nogueda with a gun when it discharged accidentally.

Police in Wichita, Kansas, say Sesmas faked being pregnant for months and had been a longtime acquaintance of the 27-year-old mother, who was found dead Thursday at her home in Wichita. 

Sesmas was jailed in Dallas on a Kansas warrant, with first-degree murder and kidnapping charges pending, and Kansas authorities are seeking her extradition.

The baby, named Sophia, who was six days old at the time of her disappearance, was reunited with family members in Kansas on Saturday.

Police say 34-year-old Sesmas faked a pregnancy for months and then traveled to Wichita on Thursday to murder Abarca-Nogueda, 27.

She then stole the woman's one-week old daughter and took her back to Texas to pass as her own.

Police tracked down Sesmas and arrested her early Saturday morning at the Dallas home she shares with her boyfriend, son and niece.  The baby was there too, unharmed. 

Police believe the other people in the home were unaware of Sesmas' alleged plans. 

She was booked in jail and is expected to be charged with first-degree murder and kidnapping. 

Sesmas had known the baby's mother for years and had spent some time in Wichita before returning to Texas to live several months ago, Wichita police Lt. Todd Ojile said. However, he did not elaborate on their relationship. Sesmas was from Texas, but had lived in Wichita for a while. 

The FBI joined in the investigation with 25 agents working on the case, Ojile said.

Late Friday night investigators identified a suspect in the case, leading them to a house in Dallas where the baby was found unharmed after a swat team executed a search warrant at 4.30am Saturday.