An escape plan by a Butler County Prison inmate charged with homicide and rape in the death of his girlfriend's son never got off the ground, authorities said.

Keith Jordan Lambing's purported pie-in-the-sky plan last month was ill conceived and doomed to fail, said Butler County Detective Tim Fennell.

“It was unlikely to have succeeded in any case,” Fennell said Tuesday, “but it was more unlikely due to the heightened security in his particular case.”

Lambing, 20, is to be arraigned via video this afternoon at the prison on a felony charge of attempted escape.

He has been behind bars since March 22 — a day after Butler Township police say he sexually assaulted 4-year-old Bentley Thomas Miller, causing internal injuries so severe that the boy bled to death.

He is being held without bail and remains in administrative protective custody — isolated from the general population — at the facility.

Lambing's alleged escape plan surfaced March 28 during a monitored call he made to a family member.

In the call, according to court documents, he told his grandmother, “I got a note I'm gonna show you when you come in and stuff, all right?”

His grandmother responds, “OK. All right. Yea,” documents said. Lambing then tells her, “I can't really talk you know.”

Later that day, a correctional officer uncovered a note in Lambing's private cell, investigators said.

The note, written on a sheet of paper, read: “On a court date they don't lock the pattywagon door.”

The note went on to suggest how someone could “get a crew to open and snip cuffs.”

Authorities believe the suspect intended to show the note to his grandmother when she came to visit him.

Fennell said it is not uncommon for inmates to hold up notes to the glass to pass on information they do not want guards to hear on the visitation phone.

But because the correctional officer had found the note, Lambing never got the chance to communicate its contents to his grandmother.

Fennell, who did not interview Lambing, said he could only speculate that the inmate's scheme was to try to get away while being driven in a prisoner transport truck to a hearing at the Butler County Courthouse.

All transported inmates are placed in handcuffs, restraining belts and leg shackles, Fennell said, which would mean any “snipping” would require bolt cutters or a similar tool.

Butler Township police accused Lambing of assaulting Bentley at a Butler Township motel where he and the boy's mother, Mackenzie P. Peters, 21, of Butler had been staying for several days.

Lambing later on the morning of March 21 called his mother, Kristen Lee Herold, 43, of Wexford and asked her to pick up the child, according to police.

Herold, prosecutors said, was driving the badly injured boy to his father's house — not to a hospital — when the child became unresponsive.

She pulled over at a Butler shopping plaza and called 911. Paramedics said when they got there, the boy was “bleeding excessively.”

Bentley was pronounced dead at Butler Memorial Hospital less than an hour later, police said.

Authorities subsequently charged Herold in the investigation after they found her March 22 in a house in Butler. Lambing was also in the house, police said, hiding in a closet ceiling.

Herold is facing trial on charges of child endangerment, reckless endangerment and hindering apprehension. She is in the county prison on $200,000 bail.

Lambing's preliminary hearing is set for April 20.

Peters on March 30 was charged with failing to seek appropriate medical treatment for her son, who also suffered a “severe burn” to the top of his hand and wrist while in Lambing's care.

She is charged with child endangerment and is facing a preliminary hearing May 11.