(NewsNation) — Lapses in security led to the escape of a Texas prison inmate that resulted in the deaths of five people, according to multiple reports citing reviews of the incident.

The reviews were conducted by The Texas Department of Criminal Justice (TDCJ) and an outside firm hired to do an independent review.

According to the TDCJ, security lapses and missed opportunities led to the escape of Gonzalo Lopez, 46, from a prison bus on May 12.

Lopez was able to break free from his restraints and cut through a caged area of the vehicle. He remained free for three weeks.

Authorities fatally shot Lopez on June 2 but not before he had killed 66-year-old Mark Collins and his four grandsons — Waylon, 18; Carson, 16; Hudson, 11; and Bryson, 11 — in what the Houston Chronicle called “one of the deadliest prison escapes in U.S. history.”

The killings occurred on the family’s ranch near Centerville, located between Dallas and Houston.

According to KHOU, the review showed that the Hughes Unit, where Lopez was housed, was less than half staffed at the time of his escape.

Both reports found correctional officers who worked at Hughes and who were with him on the bus had violated procedures by not properly searching him and not ensuring that his handcuffs were secured.

If proper searches had been done, it’s likely they would have found what resembled a handcuff key that Lopez at one point hid in his mouth, as well as two 8- to 10-inch metal weapons that he used to cut through the metal grating of a security door, allowing him to overtake the driver, according to the reports.

The TDCJ found correctional officers failed to use a device designed to quickly detect metallic contraband within the body cavities of inmates.

Leg restraints were also improperly placed on Lopez, leaving them loose, according to the review.

A device that’s put between handcuffs to block inmates like Lopez from accessing the keyhole was apparently not placed correctly and didn’t cover the keyhole, possibly helping his escape.

Additionally, two officers had falsified search logs indicating Lopez’s cell had been searched when it had not.

Both reviews found staff at the Hughes Unit “had become complacent, and circumvented security procedures in favor of hastily completing responsibilities in a cursory manner. 

The conclusions by the two reviews are similar to many of the findings found in an investigation published earlier by the Houston Chronicle and The Marshall Project. 

After the reviews, disciplinary action was taken against more than 20 staff and supervisors.

And the agency has made several changes including increasing the required number of officers to three on every transport bus and beginning the installation of video surveillance on those buses as well.

The Leon County District Attorney’s Office declined to comment on whether they would pursue charges against any officers.

The Associated Press contributed to this report.