Cruz, 19, is accused of murdering 17 people in a mass shooting at Marjory Stoneman Douglas High School in Parkland, Florida on Wednesday.
Today the FBI said it mishandled a January tip that Cruz had guns and the potential to carry out a school shooting.
Governor of Florida Rick Scott reacted with fury and said the FBI’s director should resign.
He said: “We constantly promote ‘see something, say something,’ and a courageous person did just that to the FBI. And the FBI failed to act.
“Seventeen innocent people are dead and acknowledging a mistake isn’t going to cut it. An apology will never bring these 17 Floridians back to life or comfort the families who are in pain.”
A person close to accused gunman Cruz called an FBI tip line on January 5 to report concerns about him, the FBI said in a statement.
The FBI said: “The caller provided information about Cruz’s gun ownership, desire to kill people, erratic behavior, and disturbing social media posts, as well as the potential of him conducting a school shooting.”
Other Republicans including Florida Senator Marco Rubio also harshly criticised the FBI and US Attorney General Jeff Sessions said he had ordered a review of the bureau and Department of Justice procedures following the Florida shooting.
At the funeral for massacre victim Meadow Pollack, an 18-year-old senior who had been headed to university, family friend Jeff Richman expressed disbelief at the FBI fumble.
“The FBI apologized? Tell that to families,” said Richman, 53, an advertising executive who lives in Parkland.
“Everybody always tells you ‘when you see something, say something.’ Well, here people were seeing something and saying something and it still happened.”
The FBI said the information on Cruz should have been forwarded to the FBI Miami field office, where appropriate investigative steps would have been taken, but that never happened.
FBI Director Christopher Wray said in a statement: “We have spoken with victims and families, and deeply regret the additional pain this causes all those affected by this horrific tragedy.”