The woman accused of killing an expectant mother and cutting the baby from her womb waived her right to a preliminary hearing Thursday, and a judge ruled she must remain behind bars.

Attorneys for Lisa Montgomery (search) did not ask for bond during a brief hearing before U.S. Magistrate John T. Maughmer, who granted the prosecution's request to keep her in jail. Maughmer said there is no condition, or combination of conditions, he could impose that would ensure she would appear if he released her from custody.

Montgomery, 36, of Melvern, Kan., is charged with kidnapping resulting in death. She is accused of strangling eight-months-pregnant Bobbie Jo Stinnett (search) and cutting the baby from her womb during a Dec. 16 attack at Stinnett's home in Skidmore.

Federal prosecutors have 30 days to present the case to a grand jury, which will decide if there's enough evidence against Montgomery to pursue formal charges against her. She is being held on a criminal complaint, which is only temporary, said Don Ledford, a spokesman for U.S. Attorney Todd Graves.

If the grand jury issues an indictment, Montgomery will be arraigned and enter a plea, which she has yet to do.

Clad in an orange jumpsuit, her feet chained and hands shackled at her waist, Montgomery gave barely audible one-word responses to Maughmer's questions Thursday about whether she understood her right to a preliminary hearing and whether she had been coerced into waiving that hearing.

The courtroom was filled mainly with members of the media for the roughly five-minute proceeding.

Stinnett, 23, was found by her mother in a pool of blood, her midsection sliced open. Authorities have said that on the day of the killing, Montgomery called her husband from Topeka, Kan., and told him she had just delivered a baby girl.

Authorities said the baby was found a day later with Montgomery and her husband in Melvern. The infant, named Victoria Jo Stinnett (search), spent that weekend in a Topeka hospital before going home with her widowed father.