Mark Collins and his grandsons, ages 18, 16, 11 and 11, were shot and stabbed by Lopez not far from where he escaped last month.
On Tuesday, Lt. Governor Dan Patrick said mistakes were made and he asked the Rangers to get involved to ensure they don't happen again.
Patrick said there are several questions he wants to be answered.
• How did the prisoner, who was handcuffed and locked in a secure cage inside the prison bus, remove his handcuffs, escape the cage and attack the driver?
• How did the second guard in the back of the bus not see what was happening?
• Was the prisoner fully searched as protocol required before getting on the bus?
• How was the escapee able to elude hundreds of law enforcement, bloodhounds and air patrols for several weeks?
• Was the community put on high alert after a cabin near the Collins family cabin was broken into a few days prior to their murder?
"We must answer these questions. We have a duty to all Texans to ensure this never happens to any family again," Patrick said.
Lopez and other inmates were being bussed from a prison unit in Gatesville to Huntsville for medical appointments when he overpowered the driver and hijacked the bus.
TDCJ temporarily halted most transports of violent inmates in response to the Lopez case but resumed them last week with added security measures.
"This is a crime that was preventable on several levels and should never have happened," Patrick said. "My request for investigation is not about affixing blame, but rather to ensure TDCJ procedures and protocols are adequate and always followed. There must be accountability."
Patrick said he attended funerals for the victims on Saturday.
"The Collins family is a strong Christian family. Their bold and remarkable testimony about their faith, despite this unimaginable devastation to their family, was amazing and inspiring to the 4,000 people who attended the funeral," Patrick said.