A state investigative report into the shooting, delivered to lawmakers last week, revealed in painful detail how eight sheriff’s deputies had heard gunshots but remained outside the building, wasting valuable time to try to save lives.

Sheriff Israel’s office bills itself as the largest accredited sheriff’s department in the country, with some 5,800 employees. The sheriff faced intense criticism after the shooting once it became evident that police radios jammed and deputies lacked recent training on how to handle active shooters.

The Parkland shooting has become a catalyst for the national debate on gun control. Stoneman Douglas students became youth activists for new gun legislation, and Sheriff Israel himself, who has been twice elected in a heavily Democratic county, clashed head-on with the powerful National Rifle Association. During a town hall-style event broadcast by CNN days after the shooting, the sheriff told Dana Loesch, an N.R.A. spokeswoman, that her organization was obstructing the police’s ability to keep people safe.

“You just told this group of people that you are standing up for them,” he told her. “You’re not standing up for them until you say, ‘I want less weapons.’”

Sheriff Israel then became a frequent N.R.A. target on social media. And as reports surfaced of deputies’ shortcomings at Stoneman Douglas, Republican opposition to the sheriff grew. Eventually, several vocal parents of victims whose opinions carry significant political weight also announced their lack of confidence in him.

“If you had one deputy that doesn’t go in, it could be easily called a lack of courage, or a mistake, or a fluke,” said Ryan Petty, whose 14-year-old daughter, Alaina, was killed in the rampage. “But when you have eight deputies that don’t go in when they’re hearing gunshots inside of a school, that’s a systemic failure. Systemic failures point in one direction: They point to the leader.”

Deputies told investigators they had struggled to learn what was happening the day of the massacre because their radios had jammed — the same problem they had confronted more than a year earlier at a shooting at the Fort Lauderdale airport.