LINCOLN, Neb. (AP) — Nebraska prison officials have been trying to overhaul an understaffed, overcrowded prison system for years, but violent outbursts by inmates keep slowing their efforts.

Administrators say the repeated incidents consume a large amount of time, money and manpower that could otherwise be spent on improvements. In the last two years, corrections officials have had to face a deadly riot at the prison in Tecumseh, the escape of two sex offenders and an assault that sent nine staff members to the hospital, among other incidents.

Sen. Les Seiler of Hastings, the chairman of a prisons oversight committee, says prisoners use the department’s staffing shortages to their advantage. Advocates say a lack of treatment and rehabilitation programs is also to blame.