The FBI, Boston Police and Massachusetts State Police are working at a frenzied pace to track down who is responsible for Monday's Boston Marathon bombings.

The Internet is also doing its investigative thing.

Specifically, a 4Chan Think Tank purports to have isolated a possible suspect or suspects using images taken around the time of Monday's tragic blast.

Here's one of them:

While most, if not all Internet conspiracy theories such as the mystery man on the roof are unlikely to pan out, some users say this one may have legs.

Officially, there are no suspects in the attack that killed three and injured 170 people, many severely, so maybe even the armchair detectives can help.

NOTE: THG is not labeling anyone a suspect, or claiming any knowledge of the situation, just sharing a 4Chan board we thought might interest readers.

Follow the jump for all of the "evidence" on the board so far:

UPDATE, 4/18, 5:52 p.m.: The FBI released photos of the suspects moments ago and asked for the public's help in identifying them. Here is a photo: