(NewsNation) — A former FBI agent believes the long search for an escaped Texas inmate may have been flawed.

Jennifer Coffindaffer said despite dogs, drones, heat-seeking equipment, helicopters, airplanes and hundreds of law enforcement — authorities in Texas were still not able to recapture Gonzalo Lopez before he allegedly killed five people, including children, at a home in Leon County, Texas.

Lopez had been on the run since May 12, when Texas authorities say he broke out of his restraints, stabbed a prison transport driver, took control of the bus and eventually ran away through a field.

Texas Department of Criminal Justice Chief of Staff Jason Clark said the area where the family was killed had been searched for Lopez “multiple times.” 

“(I’ve been) in charge of command posts on numerous occasions on cases like this,” Coffindaffer said. Grid searching and making sure every single area is checked and double-checked, is crucial. I don’t know where this ball got dropped.”

As to how law enforcement managed to miss Lopez despite searching the home where the family was killed “multiple times,” Coffindaffer said their grid search was likely flawed.

“I don’t have an explanation,” she said. “But if grid searches aren’t done properly, it can lead to missing where the individual is. And that seems to be what happened here.”

The Texas Department of Public Safety identified Lopez as an affiliate of the Mexican mafia and said the convicted killer had ties to the South Texas area. At the time of his escape, Lopez, 46, had been serving a life sentence after he was convicted of murdering a man with a pickax in 2005.

A spokesperson for the Texas Department of Criminal Justice told local television stations this week that the search for Lopez was the “largest concentrated manhunt,” since 2004.