(NECN/NBC News: Steve Handelsman) - In the wake of the Washington Navy Yard massacre, Defense Secretary Chuck Hagel is vowing to close what he called the gaps in the base access system. Hagel acknowledged there were red flags that warned gunman Aaron Alexis had serious mental health issues.
The chief of naval operations lives at the Washington Navy Yard. He denied Wednesday that cost cutting made the base access system less effective.
As more workers returned to the Navy Yard, the Pentagon promised to keep them safer.
"And where there are failures, we will correct them; we owe the victims their families and all our people nothing less," Hagel said.
The Defense Secretary ordered two reviews of who gets onto U.S. bases.
Two days after the Monday massacre, a year-long Navy study revealed 52 felons got passes through one clearance program, adding to the risk.
The chief of naval operations denies economics played a part.
"We don't cut budgetary corners for security, chairman," Adm. Jonathan Greenert said.
Gunman Aaron Alexis got his security pass through a tougher clearance program, but he kept it, despite clear signs his mental illness was getting worse.
It was a red flag waved August 7 in Rhode Island from a hotel in Newport. Alexis called police and told them he was hearing voices and hit by microwaves. Police notified the Navy base nearby where Alexis was working, and that contact is key to the investigation.
"What should have been done that wasn't done? Should more have been done?"
There are questions that were asked after the Fort Hood massacre in 2009. More attention was promised to mental health issues after Army Major Nidal Hasan murdered 13 people.
The mother of the Navy Yard shooter is anguished.
"Aaron is now in a place where he can no longer do harm to anyone and for that I am glad. To the families of the victims: I am so, so very sorry that this happened. My heart is broken," Cathleen Alexis said.
This, while the Pentagon vows to fix a base access system that looks broken.
One set of recommendations will come from a non-military independent panel.