It was a crime mystery that went viral and gripped a nation — but a murder "solved" by a Twitter user wasn't all that it seemed.
Certainly, the opening post by a user named Mr Brightside made people sit up and take notice.
"Police! I have just resolved a crime via Twitter! You need to deal with it immediately," Mr Brightside wrote in Spanish last weekend.
"Days ago @jor_g_t died and the case was closed as a suicide, but it was a murder and I can prove it," he continued. "The killer is in the photo."
Posting the photo in question, Mr Brightside then began to unravel what appeared to be a murder case, over a meticulous series of 100 tweets, the BBC reports.
Based on one picture, Mr Brightside claimed he could prove the death in Barcelona of an acquaintance which had been ruled a suicide was in fact a murder.
He said the dead man, known as Jorge A, was killed as a result of an elaborate polyamorous plot.
His tweet-by-tweet whodunit revealed a mistake in the vital picture had led him to the person he believed was Jorge A's killer — a man named Will.
By now, Mr Brightside's tweets had been read and shared by millions.
Even Spanish police were in on the act, tweeting a reply. "Your research confirms the report of our investigators. Will and his accomplices will spend some time in prison."
They added an advisory: "If you are a victim of sextortion, the police will help you. Don't give in to blackmail."
Case, it seemed, closed.
Or it would have been, if any of it was true.
Turns out, Mr Brightside's story was a complete lie.
There hadn't been a murder, a love triangle or a suspect.
Because nobody in that vital photo actually existed.
The ultimate troll
Mr Brightside had come up with the ultimate troll — and a lesson for social media users — as part of a competition organised by Twitter Spain, in which users were asked to tell a story via a series of tweets.
Mr Brightside's story was so attention-grabbing that it spiralled out of control.
Some realised the whole thing was pure fiction: finding clues that all was not quite as it seemed.
Like the fact the Twitter accounts of the story's main protagonists — Will, Jorge A, Luis and Felipe had all been created in the past fortnight. And they only followed each other, and a number of celebrities.
Then there was the giveaway hashtag Mr Brightside added to his final tweet: #FeriadelHilo (meaning "thread festival", the name of the competition).
Turns out, police weren't fooled either: their Twitter response gave a nod to the competition hashtag. Not to mention police wouldn't convict a murderer via Twitter.
Two days after the 'murder solved' thread went viral, Modesto García a graphic designer from Madrid, 'fessed up to the hoax.
Confirming Mr Brightside and the killer conspiracy were pure fiction, he said the police involvement had been an unexpected bonus which gave his fake story even more legs.
"I did not ask them [police] to collaborate in the story," he told the BBC.
"They did it because they wanted to and, thanks to that, the story gained a lot of credibility."
How he did it
Mr Garcia's fake case was built on Jorge, a fictional 30-year-old who had recently moved to Barcelona.
Mr Garcia's snoopy alter ego — Mr Brightside — claimed to have been following Jorge's Twitter account and was puzzled by his sudden death by suicide, so dug deeper.
Garcia had doctored the photo by combining images and the faces of some of his friends, as well as himself.
The picture featured Jorge — the "dead man" — in the middle — and included a deliberate fault: lettering on a T-shirt appearing reversed, yet a tattoo on Jorge was not.
It was one of the many pieces of "evidence" Mr Garcia added to his tale of conspiracy — allowing Mr Brightside to conclude the picture was part of a cover-up.
As the story progressed, Mr Garcia drew in the fictional characters on their Twitter accounts, until finally accusing "Will" of a deadly plot.
Mr Garcia created his fictional characters' social media profiles using stock images, and peppered the accounts with unrelated tweets to make them look real.
But some readers spotted he'd made the mistake of creating them all on the same day.
The moral of the story
Mr Modesto told the BBC that he was utterly shocked by the story's popularity.
"People have written to me from Brazil, Ecuador, Mexico, the Dominican Republic, Peru …"
Fans have created memes, replacing the figures in the picture with their own suggested suspects.
Mr Modesto said he did not plan it as a fake news experiment.
"I only expected 200 people to like it, at most," he said.
"The moral is: don't believe everything you read on the internet."
Twitter Spain will announce the winner of the thread competition this weekend.
First prize is 500 euro ($840), a smartphone and a mystery gift.