WASHINGTON The lone gunman keeps law-enforcement officers across the country awake at night.
Hes hard to pick out of a crowd. He has no criminal record. Often, he hasnt told anyone about his plans. Hes compiled a weapons cache legally. He doesnt show up on any law-enforcement radar until after hes acted.
The government has been more successful stopping al-Qaida from pulling off another Sept. 11-type attack than it has in preventing deadly shooting sprees such as the one in the movie theater in Aurora.
Law-enforcement officials say its nearly impossible to stop someone such as James Holmes, the intelligent 24-year-old who, officials believe, killed 12 people and injured dozens of others.
The threat of the lone offender has become such a concern that the FBI in 2009 created a more than 25-member task force to identify common behavioral traits and characteristics. In 2012 alone, there have been 22 mass shootings, according to the Brady Campaign to Prevent Gun Violence.
To stop al-Qaida, the government attacked terrorist hideouts, froze major sources of terrorists funding and made it more difficult for them to acquire weapons and materials to build bombs.
Holmes does not appear to be part of any terrorist or criminal network; officials say his purchases were legitimate and raised no red flags. There will be no easy or quick answers and maybe there will never be any answers, the Aurora police chief, Dan Oates, told CBS Face the Nation, adding that all the evidence gathered so far indicates he wasnt particularly aided by anyone else.
Until Friday, Holmes did nothing to bring him to the attention of law enforcement.
Theres no way you can prevent it. Theres absolutely no way, said Peter Ahearn, a former FBI agent. It was random. It happened. There was nothing that could have prevented that unless someone saw him loading his car with guns.
The Department of Homeland Security runs a nationwide If You See Something, Say Something campaign. Ads encouraging people to report suspicious activity are displayed around the country, including in some movie theaters, the department said.