Two women who police say killed two children while performing what they thought was an exorcism will continue to be held without bond as prosecutors seek a psychiatric evaluation to determine if they are mentally competent to stand trial.

The women, 28-year-old Zakieya Latrice Avery and 21-year-old Monifa Denise Sanford, have told investigators that they believed evil spirits moved successively between the bodies of the children, ages one and two, and that an exorcism was needed to drive the demons out, said Montgomery County State's Attorney John McCarthy.

The women also reported seeing the eyes of each of the children blackening and after the intended exorcism took a shower, cleaned up the scene and "prepared the children to see God," McCarthy said. The children's two older siblings, a five-year-old girl and an eight-year-old boy, were also found injured with stab wounds. Avery is the mother of all four children.

Part of 'demon assassins,' suspects claim

The girl remains in critical condition but the boy was close to being released from the hospital as of Tuesday afternoon. The two older children might have died had a neighbour not called the police emergency dispatcher, police said.

Germantown Deaths

Two of Zakieya Latrice Avery's children, a 1-year-old and a 2-year-old, were found dead by police, who were answering a neighbour's 911 call. (Montgomery County Police Dept./The Associated Press)

Avery and Sanford appeared for a court hearing via video conference Tuesday on charges of first-degree murder and attempted first-degree murder. They face a sentence of life in prison if convicted.

The women identified themselves to investigators as members of a group known as the "demon assassins," and police are looking to interview other people who might be part of the same organization but say there are no other suspects.

When being questioned by police, McCarthy said, the women told investigators that they tried multiple methods to remove the presence of demons from the children, progressing from an attempt to break the neck of the youngest child to strangulation to stabbing.

Edward Leyden, a lawyer for Sanford, told reporters after the brief hearing that "everyone who is involved in this case is in deep pain."

"It obviously has details that are salacious and we just ask folks to give an opportunity for all of us to get a handle on just what happened here," Leyden said of the case, "so that when the time comes to present this to a judge and a jury, all of the facts are here."

A lawyer for Avery did not return a call seeking comment.

Avery had been living for months in a townhome community in Germantown - about 48 kilometres northwest of Washington - with her four children, and recently, with Sanford. The father of the children does not live in the area, police have said.

A District Court judge directed Avery to undergo a psychiatric evaluation to determine whether she is ready for trial and prosecutors plan to make a similar request of Sanford when she has a bond review hearing Friday.

The question of whether either woman intends to submit an insanity defence has not yet been raised as the two will first need to be evaluated and then deemed competent for a murder trial.

McCarthy said Avery had previously been involuntarily committed for mental health treatment and that Sanford told investigators that she had previously tried to commit suicide.