NEW CASTLE, Pa. - Lawrence County District Attorney Joshua Lamancusa told 21 News that investigators are still looking for a motive after finding no signs of drugs or evidence that anything of value was taken when two adults and one child were shot to death at a New Castle home on Tuesday.

Lamancusa also said on Thursday that another person is being sought by police in addition to Procopio.

He did not identify the suspect.

Police say one of the suspects is a former babysitter for ten-year-old Amariah Emery, who along with her 31-year-old mother Nichole Pumphrey and 31-year-old Lawrence Cannon were found shot to death in Pumphrey's West North Street home early Tuesday.

Nineteen-year-old Stephen Procopio was picked up by police late Wednesday.

New Castle Police Cheif Bobby Salem tells 21 News that Procopio knew Pumphrey and her children.

“We believe he used to babysit the children. He was an acquaintance with Nichole,” said Salem who did not say if investigators have a motive for the shooting.

A woman, identified as Jody Hammer, who lives in the same home as Procopio, was also arrested on charges not related to the homicide after police discovered a marijuana-growing operation while searching the home at 258 Canterbury Road.

Investigators say all three victims were shot. Pumphrey had been shot twice.

According to our NBC affiliate, WPXI in Pittsburgh, Emery was shot as she was coming down the stairs. 

Salem told 21 News that detectives first questioned Procopio and Hammer just hours after the discovery of the shooting. The following day the two were questioned again for five hours, and this time they were arrested.

Lamancusa says investigators interviewed some of the four children who were at the home during the murders, but he did not say what information they provided.

Procopio is in the Lawrence County jail and is expected to appear before a district magistrate to answer three counts of criminal homicide.