Despite all this, Alexis still managed to find work at The Experts for about six months over the past year. That company said the last of two background checks it conducted in June on Alexis "revealed no issues other than one minor traffic violation."
Like the military, The Experts has come under criticism for not recognizing Alexis as a potential problem or threat.
A Hewlett-Packard spokesman told CNN on Wednesday the technology company -- citing its policy of adhering "to the highest standards of business practices and ethics" -- had dropped The Experts as a subcontractor.
"Based on what we now know about The Experts' conduct, including its failure to respond appropriately to Aaron Alexis' mental health issues and certain incidents recently reported in the press, HP has terminated its relationship with The Experts," the spokesman said.
The Experts responded, in a statement, saying it was "disappointed' by HP's decision and insisting it has met "all of our contractual obligations."
"The Experts had no greater insight into Alexis' mental health than HP, particularly given that an HP site manager closely supervised him, including during the events in Rhode Island," the company said.
FBI takes heat over video release
The FBI was criticized Wednesday night, both by Defense Department officials and victims' families following the release of the video.
"People in DoD are furious that FBI and other law enforcement officials unnecessarily put out this video footage today. It only adds to the pain of the families and brought life back to a killer," a senior Pentagon official told CNN. "Outside of law enforcement channels, the video was not viewed."
Another Defense Department official described the release as "gratuitous," indicating there was nothing to be gained from the release.
Law enforcement officials said they reached all but one of the victims' families to inform them beforehand.
And officials at the FBI argued that the video clarified various conflicting reports about the timeline of events, and would help to dispel various pieces of misinformation, including one incorrect story that the shooter was looking for specific victims.
Ronald Hosko, assistant director of the FBI's Criminal Division, said what was released was a far less painful version of the graphic video collected by authorities.
Navy leadership said that while officials knew the footage would be released, they were not told of the content. It is not known if anyone in Pentagon leadership had expressed their views with the FBI or Justice Department.
Sources also told CNN that the Naval Criminal Investigative Service, an arm of the Navy, was part of the decision regarding the distribution of the video, and saw the footage before it was released.
One victims' family reacted with equal dismay.
"I'm in total shock after reviewing the video. We have not even had time to begin to grieve," Theodore Hisey told CNN Wednesday evening, saying his family did not know the FBI was about to release the video.
His sister-in-law, Mary Francis Knight, was one of the 12 killed by Alexis.