One of the most lasting lessons that came out of the way law enforcement handled the Boston Marathon bombing came in the Twitterverse, where the Boston Police Department provided a clear beacon for using the social media platform.

The Boston PD's public information bureau steadied the nerves of its rattled city with its constant stream of Twitter updates about the bombing, manhunt, and eventual capture of the remaining suspect.

Cheryl Fiandaca, the bureau's chief, offered the first tweet on April 15: "Boston Police confirming explosion at marathon finish line with injuries. #tweetfromthebeat via @CherylFiandaca."

She set the record straight about the reported arrest; offered the first image of Dzhokhar Tsarnaev; and relayed this joyous news: "CAPTURED!!! The hunt is over. The search is done. The terror is over. And justice has won. Suspect in custody."

In the process, the agency added nearly 300,000 new followers and has become the most followed law enforcement agency on Twitter.

Fiandaca provided a model for the possibilities of Twitter for law enforcement during a critical incident, as agencies continue to explore the possibilities of a social media platform inspired by the clipped, coded messages of public safety dispatchers.

In late April, "web intelligence" firm Bright Planet offered a deep dive into how police agencies are using Twitter. Nearly 3 million people are following the 772 active law enforcement accounts. The most common types of tweets from agencies report "police activity updates" and traffic alerts, according to research presented in an infographic.

The Boston PD's Twitter feed (@Boston_Police) had 332,219 followers as of the time of the study. In the days following the bombing, the agency increased its number of followers by 514 percent from 54,087 on April 2.

Other top-followed agencies include the Masachussetts State Police (32,502 followers), Baltimore PD (31,256), Seattle PD (29,469), New Jersey State Police (22,758), and Kansas City PD (21,230).