'Love During Lockup' Star's Estate Sues Prison Over His Suicide

“Love During Lockup” star Justin Johnson’s estate is suing officials in charge of the prison where he was incarcerated when he died by suicide ... alleging the guards there didn’t monitor him closely enough.

The administrator of Justin’s estate -- his grandmother, Paulette J. Spackman -- filed the lawsuit against the superintendent and multiple correctional officers at SCI Houtzdale ... a state prison located in Pennsylvania.

Spackman says the officers are required to visually confirm the condition of each inmate at regular intervals ... but, on the night of Justin’s suicide, she claims officers left him alone for 90 minutes with a covering over his window.

Per the docs, Justin wasn’t even discovered dead by a corrections officer ... instead, she says his cellmate came back to their shared room and found him hanging from the ceiling. She says his body was already cold to the touch.

Spackman also notes Justin had a documented history of mental health and substance abuse issues.

She’s suing the officials for supervisory liability/failure to train and supervise, deliberate indifference, and wrongful death.

Justin appeared on a recent season of “Love During Lockup” ... and died in prison just months after the season aired.

He was just 35 years old.