Davis gained national stature after the April 15 bombing that killed three people and wounded more than 260 others, and the ensuing manhunt that ended several days later when one suspect was killed in a police shootout and another was arrested in neighboring Watertown. He appeared the following month before a congressional committee in Washington to discuss the sharing of information between city police and federal anti-terrorism officials.

Davis called the Boston Marathon bombing one of the hardest and high-profile cases he's had to work on but also mentioned the countless other, smaller ones that officers worked long and tirelessly on, CBS Boston reports. 

"It's time for me to try other things," Davis said at a news conference at police headquarters in which he thanked Boston Mayor Thomas Menino for showing him the importance of connecting with the community. He also thanked his command staff, the department's rank-and-file officers and even the heads of police unions, with whom he generally had a far less adversarial relationship than some of his successors.

Davis said he would leave the post in the next 30 to 60 days, saying his exact departure date might hinge on the success of the Boston Red Sox. If the team was to advance to the World Series, Davis indicated he might stay on, presumably to coordinate crowd control in the event of a victory celebration, said the Boston Herald.

"Over the past seven years, Ed Davis has served the people of Boston with integrity, a steady hand and compassion," Menino said in a statement , adding that serious violent crime had decreased in the city during the commissioner's tenure.