The FBI came under fire once again on Friday after reporting that it had ignored investigative protocol regarding a tip it received in early January about NIkolas Cruz, the 19-year-old suspected shooter accused of killing 17 people in Parkland, Florida, on Wednesday.

A person close to Cruz warned the FBI that he was a gun owner, desired to kill people, displayed erratic behavior, posted disturbing social media posts and had the potential to conduct a school shooting. Such tips are fairly common for the nation’s top law enforcement agency, which relies heavily on the public to help prevent or solve these types of crimes, according to John Iannarelli, a former FBI agent.

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“Obviously, something broke down along the way,” Iannarelli told FOX Business’ Ashley Webster during "Countdown to the Closing Bell." “But it could very well be because the FBI received so much information, deciding what to triage. What needs to be looked at immediately versus what is going to be looked at later on.”

Before the shooting at Marjory Stoneman Douglas High School, Cruz displayed violent and erratic behavior and had a number of run-ins with law enforcement, according to reports. But despite repeated calls to authorities, he was not arrested until Wednesday, when he allegedly began firing a legally obtained AR-15 at students and faculty members. He was charged with 17 counts of premeditated murder on Thursday and is being held without bail.

Attorney General Jeff Sessions has ordered Deputy Attorney General Rod Rosenstein to conduct an immediate review of the Justice Department and FBI’s procedures to ensure the agencies are swiftly and effectively responding to indications of possible violence.

Most likely, the FBI did not immediately follow up on the tip because the agency is inundated with similar tips multiple times a day in every single city, said Iannarelli, adding that he didn’t want to excuse the blunder.

“There are thousands of leads daily, and the FBI has to respond to every single one of them,” said Iannarelli, noting that there are roughly 12,000 FBI agents worldwide. “It’s not the success of the one you prevent. It’s the one you miss that causes all the problems.”

“The FBI, along with law enforcement in general, there’s not enough people. The FBI has what Congress will afford the FBI to have, whether it be bodies or finances,” he said.