TODAY | April 17, 2013
>>> with more on the boston marathon bombing. this morning, law enforcement officials are keeping a very close eye on the internet, specifically sites that show people how to make destructive devices. nbc's senior investigative correspondent lisa myers has that part of the story, good morning.
>> matt, good morning to you. regardless of who committed this atrocity it's clear these days that anyone with a grievance and the will can learn how to become a terrorist simply by going online. now authorities are trying to use some of these sites to their advantage. the latest evidence bomb makers have taken their teachings to the web this online al qaeda publication posted last month, a guide to carrying out terror attacks including detailed illustrated recipes for pressure cooker bombs, the kind investigators say was used in boston.
>> the internet has brought terrorism to the web. it's made it go viral. anybody can look online and find out how to make a bomb. it is a frightening development.
>> a similar terrorist manual, how to make a bomb in the kitchen of your mom, was posted three years ago. prosecutors say it was used by this former muslim- american soldier who wanted to bomb a restaurant popular with soldiers at ft. hood, texas. anarchists and white supremacists have featured pressure cooker bomb formulas on their websites.
>> there are descriptions for how to make this kind of bomb on many websites in every major language and ordinary search engine will take you to them.
>> reporter: it's a far cry from the days when terrorist bomb makers used to train others in person in secret camps in remote places. now everything's online, available any time, anywhere, to anyone, and it's not just bomb recipes. there's all kinds of information a terrorist could use. in fact, the how to guides are so numerous, some counter-terror experts no longer object to the media reporting about them.
>> the bad guys have the information. it's time we let the general public know what's out there so they know what it is they have to worry about and what we're dealing with.
>> reporter: u.s. authorities can't block all sites, they now try to use the sites to track down potential terrorists or even thwart them.
>> we've been told in the international intelligence community there's been some influence in the recipes and changing them.
>> reporter: experts say the easy availability of bomb-making formulas does not seem to have increased the frequency of attacks but worried it may make the successful ones more lethal.
>> lisa myers in washington, thank you very much.