While officers raced to a recent 911 call about a man threatening his ex-girlfriend, a police operator in headquarters consulted software that scored the suspect's potential for violence the way a bank might run a credit report.

The program scoured billions of data points, including arrest reports, property records, commercial databases, deep Web searches and the man's social- media postings. It calculated his threat level as the highest of three color-coded scores: a bright red warning.

The man had a firearm conviction and gang associations, so out of caution police called a negotiator. The suspect surrendered, and police said the intelligence helped them make the right call — it turned out he had a gun.

As a national debate has played out over mass surveillance by the National Security Agency, a new generation of technology such as the Beware software being used in Fresno has given local law enforcement officers unprecedented power to peer into the lives of citizens.

Police officials say such tools can provide critical information that can help uncover terrorists or thwart mass shootings, ensure the safety of officers and the public, find suspects, and crack open cases. They say that last year's attacks in Paris and San Bernardino, Calif., have only underscored the need for such measures.

But the powerful systems also have become flash points for civil libertarians and activists, who say they represent a troubling intrusion on privacy, have been deployed with little public oversight and have potential for abuse or error. Some say laws are needed to protect the public.

In many instances, people have been unaware that the police around them are sweeping up information, and that has spawned controversy. Planes outfitted with cameras filmed protests and unrest in Baltimore and Ferguson, Mo. For years, dozens of departments used devices that can hoover up all cellphone data in an area without search warrants. Authorities in Oregon are facing a federal probe after using social media-monitoring software to keep tabs on Black Lives Matter hashtags.