LIMA, Ohio — Convicted school shooter T.J. Lane's escape from the Allen Correctional Institution Thursday night followed 18 months in prison in which he was disciplined seven times.

In August, prison officials cited Lane, 19, for urinating on a wall in the Allen Correctional Institution. Prison officials took away Lane's recreation privileges for seven days, a prison official told The Plain Dealer earlier this week.

It was the latest incident in which Lane displayed his struggles at adjusting to prison life. For months, he had been in protective custody, but it is unclear whether he was there at the time of his escape.

Lane was serving three consecutive life sentences for killing three students and wounding three others at Chardon High School on Feb. 27, 2012. He pleaded guilty to three counts of aggravated murder, two counts of attempted aggravated murder and one count of felonious assault.

In July 2013, he was ordered to spend 10 days in segregation on a prison charge of "self-mutilating, including tattoo," or giving himself a tattoo. A month later, he refused to carry out a work-related or institutional assignment and was given a verbal reprimand.

In October 2013, he was charged with doing the same thing, losing 10 days of recreation time, JoEllen Smith, a spokeswoman for the Ohio Department of Rehabilitation and Correction, said Monday.

Lane also faced punishments for at least three similar offenses this year. The latest came Aug. 28, when Lane was punished for urinating on the prison wall, The Plain Dealer learned.

He originally was taken to the Lorain Correctional Institution within days of his sentencing in Geauga County Common Pleas Court in March. He was later transferred to the Corrections Reception Center near Columbus and later to the Lebanon Correctional Institution.

He is one of more than 400 inmates serving life in prison without parole, according to state prison records. And as one of the youngest, Lane could cost state taxpayers about $1.4 million if he lives to the age of 80, according to estimates based on the current annual cost of $22,836 per inmate.

Lane admitted that he killed students Demetrius Hewlin, 16; Russell King Jr. 17; and Daniel Parmertor, 16, on Feb. 27 in the school's cafeteria. Injured in the shooting were students Joy Rickers, Nick Walczak and Nate Mueller.

At his sentencing in March 2013, Lane took off a blue dress shirt and revealed a T-shirt with the word "Killer'' on it. Lane wore a similar shirt when he opened fire in the school cafeteria.