“It shocks me how I can look up my name on Google or on YouTube, and it’s going to pop up everything,” Mr. Gonzales said recently in Florida, where he moved to escape the notoriety that came with his arrest, but has still been unable to find steady work. “My kids, their kids, can always look up and they can see, oh, he was arrested for capital murder.”

The potential for inaccurate information about a tragedy to spread quickly and ruin lives has drawn increased attention amid a high number of violent gun attacks this year and since the release of the movie “Richard Jewell,” which tells the story of a man who was wrongly implicated by the news media in a bombing during the 1996 Atlanta Olympics.

In the highly competitive news environment that follows a mass shooting, reporters sometimes fall for malicious disinformation online, such as after the school shooting in Parkland, Fla., or cite unnamed sources who may or may not be right. In other instances, when the police provide on-the-record information that later turns out to be wrong, news articles initially report information incorrectly and sometimes those details continue to live online. Like many local and national news outlets, The New York Times wrote about Mr. Gonzales’s arrest and published his mug shot. The Times also wrote an article when he was released.

“There’s balancing priorities between wanting to get the facts right, and knowing that the first information you get is usually inaccurate or wrong, and the public’s right to know,” said Chuck Wexler, who leads the Police Executive Research Forum, which advises departments on best practices. He described briefing reporters after a mass shooting as “piecing together a jigsaw puzzle instantly.”

In Santa Clarita, Calif., where a gunman shot five people last month at a high school, the sheriff’s office was initially duped by an Instagram account that they wrongly linked to the gunman. Reporters, who had been reassured by law enforcement officials vouching for the postings, had to backtrack after publishing excerpts.