From YouTube to obscure blogs and even the Guardian's own comment section, the internet has had access to a huge amount of footage from last week's Boston Marathon explosions. Sure as day follows night, the conspiracy theorists have used this multitude of information to concoct multiple alternative scenarios, considerably more colourful than the "official" accounts.

These theorists had an unusually loud voice the night of the 15 April attack, when a "correspondent" for the conspiracy site Infowars asked Massachusetts governor Deval Patrick if the explosions were a "false flag attack." On Tuesday, the Associated Press said that suspect Tamerlan Tsarnaev, now dead, was a fan of the notorious "alternative news" site – a claim Infowars founder Alex Jones is distancing himself from.

To protect your pristine search history, here's a round-up of some of the prevailing theories dominating online comments, Reddit threads and the inboxes of reporters.

The Boston bombing is a false flag attack

In a nationally televised press briefing, Infowars' Dan Bidondi asked: "Is this another false flag staged attack to take our civil liberties and promote homeland security while sticking their hands down our pants on the streets?"

The "false flag" term describes a falsified attack that is used to justify expanding government power. It has origins in naval warfare, according to this in-depth Atlantic Wire explainer. Bidondi clearly thinks the government orchestrates fatal attacks to take away the civil liberties of US civilians.

New Hampshire state legislator Stella Tremblay also believes this, as seen by her endorsement of the theory on Glenn Beck's Facebook page. According to the Huffington Post, Tremblay once emailed a doctored video that "proved" Barack Obama was not born in the US to her fellow House members. Also, one of Tremblay's advisers said that the US is still under the control of Queen Elizabeth II.

Organizers knew the attack was going to happen

One popular theory centers on an account by Boston Marathon runner Alastair Stevenson, who said a bomb drill was held before the event. "At the starting line this morning, they had bomb sniffing dogs and the bomb squad out there," Stevenson told Alabama.com. "They kept announcing to runners not to be alarmed, that they were running a training exercise."

This theory relies on the testimony of one person who has experienced a highly traumatic event, but many theorists are using it as a key piece of evidence, choosing to ignore the frequent appearance of bomb sniffing dogs and crews at major events in the US. It also remains unclear why organizers would run a bomb drill before setting off an explosion.

An image released on 19 April 2013 by the FBI showing two suspects in the Boston Marathon bombing. Photograph: Handout/FBI via Getty Images

The naked arrestee

Some theorists have seized on a report that emerged during the Thursday night information spill that occurred after authorities announced the suspects had been located. Police arrested a naked man who some news agencies hastily said was one of the bombing suspects. This turned out not to be the case, but some theorists choose to believe that the man in this grainy arrest video is Tamerlan Tsarnaev, who was killed during the manhunt. They think this because he has dark hair and a similar complexion.

The New York Post's suspect is guilty

The New York Post irresponsibly identified two young men as suspects on the front page of their paper. Shortly after the attacks, the Post erroneously reported that one suspect was a "Saudi national". One of those men has been bait for the conspiracy theorists who choose to believe he is responsible. This theory is featured on blogs that say such things as: "Is it good to be afflicted with Islamophobia?" A question rhetorically asked with the assumed answer of yes.

These theorists also believe he is responsible because Michelle Obama apparently visited him in the hospital, secretary of state John Kerry supposedly had a private meeting with the Saudi foreign minister after the New York Post article came out, and Barack Obama supposedly had an unscheduled meeting with the US ambassador to Saudi Arabia.

Uncle Ruslan and the CIA

Daniel Hopsicker's Madcowprod.com claims to contain "investigative reporting into the drugs trade, 9/11, and state-sponsored crime." His Boston Marathon "investigation" suggests that the bombing suspects' uncle, Ruslan Tsarni, worked with the CIA, Chechnyan crime bosses and other groups often to be found in a second-rate thriller. It's unclear what these purported connections have to do with the suspects' motivations for the explosion – but there is talk of peacock-feathered stilt-walkers and ice sculptures of nude people.

Boston Globe tweets about an explosion before it happens

The Boston Globe sent out tweets saying a controlled explosion would be happening on Boylston Street, the scene of the attack. The theorist-friendly twist? These tweets were apparently sent before the explosions happened. Instead of trying to figure out why the Boston Globe would send out tweets just before an explosion without any context, read this snappy debunking of the theory by the Globe's senior product manager Damon Kiesow. Basically, tweet times match the time zone of the account reading them.

Memorial Pages created a moment too soon

More from the ever-reliable social media world. Two Facebook pages memorializing the attack were allegedly created before the explosions. Facebook lesson: users can choose the date their page was created, started, founded, etc. That's it. What is worth questioning is: why would anyone create a memorial Facebook page for a tragedy they knew was going to happen?

The Boston Marathon bombing poses searching questions for counter-terrorism agencies across the world. Photograph: David L Ryan/AP

Tamerlan Tsarnaev: FBI informant?

Russian security services approached the FBI for information on Tsarnaev in early 2011 because of his radical opinions. Yet when Tsarnaev returned to the US in 2012, he was not flagged by US authorities. Conspiracy theorists see this as evidence that Tsarnaev was an FBI informant, because he was apparently suspicious enough to be suspected but not enough to be extensively investigated. Some conspiracy theorists apparently have considerable faith in the US bureaucratic system.

Military contractors were at the bombing, and therefore caused it

Two men wearing hats and backpacks and who are not the Tsarnaev brothers can be seen in photos before and after the explosion. The prevailing conspiracy assumption is that they are military contractors who orchestrated the attack – not authorities present at the event for security. Alex Jones and the Infowar crew are fond of this "evidence".

The many defenses of Dzhokhar Tsarnaev

Theorists have raised a number of questions about Dzhokhar's involvement in the explosions. There are claims that photos of him at the scene were photoshopped, and questions of the veracity of accounts of his capture in a Watertown, Massachusetts boat. One of the most dominant theories in this collection is that Dzhokhar walked away from the scene with his backpack in hand. The picture that "proves" this is here. Dzhokhar is in the white hat.