Image copyright Shutterstock Image caption A sorority house was one of the 22-year-old's targets

Minutes before Alek Minassian allegedly launched Monday's deadly attack in Toronto, Canada, he posted to Facebook: "The Incel Rebellion has already begun! We will overthrow all the Chads and Stacys! All hail the Supreme Gentleman Elliot Rodger!"

Police have not yet confirmed any motive for the attack in which he is accused of murdering 10 people but his post on Facebook has drawn new attention to a mass murderer whose crimes inspired a dubious following.

Image copyright Facebook Image caption Facebook have confirmed the screenshot is genuine

Elliot Rodger killed six people in a stabbing and shooting spree in Isla Vista, California, in May 2014.

Before he turned the gun on himself, the 22-year-old posted a "retribution" video to YouTube and emailed a lengthy autobiographical document to almost two dozen people he knew.

An online community known as the "involuntarily celibate", or incels, who blame women for their sexual failings, fastened upon the document.

What did Rodger believe?

Son of a Hollywood filmmaker, he grew up in a life of privilege and relative affluence. The 141-page document he distributed in his final hours explores that upbringing, his mental health and his deep-rooted loathing of women, fuelled by an intense frustration over his virginity.

Image copyright Shutterstock Image caption In the document Rodger proclaimed: "I am the closest thing there is to a living God"

On the video he posted to YouTube, Rodger sat in a BMW car his family had given him and complained about being a virgin at 22, saying he had "never even kissed a girl".

In the document, he described himself as the "ideal magnificent gentleman" and could not comprehend why women would not want to have sex with him.

He planned his murderous rampage as a "Day of Retribution" and said he had "no choice but to exact revenge on the society" that had "denied" him sex and love.

Rodger specified that he planned to target the Alpha Phi sorority whose members he had deemed the "hottest" at his college, "the kind of girls I've always desired but was never able to have".

He shot and killed Katherine Cooper, 22, and Veronika Weiss, 19, members of another sorority, outside the Alpha Phi house.

He also stabbed to death three young men: Cheng Yuan Hong, 20, Weihan Wang, 20, and George Chen, 19.

He injured 14 when he travelled around firing at random in his car and fatally shot Christopher Michaels-Martinez, 20.

In the final section of the manifesto, Rodger declared: "I am the true victim in all of this. I am the good guy."

How is Rodger idolised by his fans?

He has been virtually canonised by some fringe communities online. A mock film trailer for "The Supreme Gentleman" in his honour, cut from his clips, was still available on Wednesday on YouTube almost four years after its original upload.

Several versions of these videos, which the BBC raised with YouTube, have now been deleted.

Image copyright YouTube Image caption The videos had been viewed thousands of times (left) but have now been flagged for removal

In a statement the website said that videos threatening violence contravened their guidelines.

"We encourage anyone who sees material that they think crosses the line to flag it for us," YouTube said.

But lots of fan videos about the rampage killer, and his old YouTube channel, still remain online.

T-shirts of selfies with him posing in sunglasses could also be purchased online through international self-print clothing retailer Redbubble on Wednesday.

After the BBC raised the items to the market website, they removed the content as per their guidelines.

Image copyright Redbubble Image caption The platform is intended for artists to print their work but Rodger merchandise is available for sale

In December the social news website Reddit banned an incel discussion group (subreddit) as part of its efforts to cut down on violent content and illicit item sales.

However, independent platforms and aliases have sprung up in its place, leading to a cat-and-mouse game with moderators.

On dedicated incel websites, users are split. Some disavow Rodgers but others admire him, seeking to rationalise and even celebrate his actions. Likewise the attack attributed to Alek Minassian.

Of the Toronto suspect, one post says: "I hope this guy wrote a manifesto because he could be our next new saint."

Another proclaims: "I will have one celebratory beer for every victim that turns out to be a young woman between 18-35."

What is the 'manosphere'?

The incel community is just one of the misogynistic groups that exist within the so-called "manosphere" - a web of online blogs and forums which reject mainstream conceptions of gender inequality.

Others include Men Going Their Own Way (MGTOW), a group which focuses on male self-ownership and believes men have been disadvantaged by modern society's development.

Arguably the best known group is the "The Red Pill" - a Reddit subforum with more than 200,000 members which says its focus is a "discussion of sexual strategy in a culture increasingly lacking a positive identity for men".

The ideologies are often confounded with others, including the self-dubbed "alt-right", so imagery like Pepe the Frog is popular.

The forum's name is a reference to the 1999 film The Matrix and refers to a pill the main character must swallow in order to see "dark truths" about the world around him.

In 2017 New Statesman journalist Amelia Tait spoke to several former members about their online radicalisation, unveiling bullying and indoctrination techniques within the community.

She summarises the forum's ideology as a profound belief that "feminism is toxic, sexism is fake, men have it harder than women and everything the media teaches about relationships is a lie".