Much-loved TV presenter Jill Dando was murdered on her doorstep in April 1999 but her killer has never been found.
BBC documentary The Murder of Jill Dando has explored the possible theories behind the Crimewatch host's tragic death.
Jill, 37, was gunned down in the middle of the day on her doorstep in a crime that shocked the nation and left the police following multiple leads.
Her murder still remains unsolved and Met Detective Chief Superintendent Hamish Campbell admitted it would probably stay that way.
Here are the possible theories behind her murder:
Crimewatch killer
Jill Dando's Crimewatch co-host reveals secret kind thing she did for him live on air
One possible theory was that Jill's death was related to her Crimewatch presenting duties.
There was claims that someone may have targeted her for being the "messenger".
However, her co-host Nick Ross rubbished the theory on tonight's BBC documentary.
He said: "Right from the beginning there was this assumption it was something to do with Crimewatch.
"To go for someone who is just the messenger? Why? Sure she was the Crimewatch presenter, but why not for presenting the holiday programme? Why not just because she is famous?"
Serbian revenge
Some insisted that Jill's death was a retaliation to Nato forces bombing Serbia.
Three days before the assassination a British bomber had hit Radio Television Serbia and killed 16 members of staff.
Jill's sister Judith was told by their mum that one of the victim's was "the Serbian Jill Dando".
Speaking in the documentary, she said: "My mother did tell me the Serbians had said when they bombed their broadcasting station that we’d killed the Jill Dando of Serbia.
"The fact it might have been a tit for tat reprisal, I can understand that might be the case, particularly since the way Jill was killed it makes me think it's related to something bigger than the actual act.
"It doesn’t mean to say that was what happened but i can see that is what happened
Someone she knew
Another theory is that Jill was murdered by someone she knew.
The police came up with a list of possibilities including revenge, money, sex, jealousy and ex-boyfriends.
Her sister Judith said: "They always say most people who are killed are killed by someone they know.
"You question everything and question everyone's motives in turn and think 'could they be the one who did it?'"
Stalker
Dando's time in the limelight and large public following led police to question whether a member of her fan base had been responsible.
Around 140 people were said to be 'obsessed' with the star by the police and she received thousands of letters.
Met Detective Chief Superintendent Hamish Campbell said some had sent her sexually explicit fan mail.
He said: "There were some odd letters she received and one individual who was clearly obsessed."
This theory was largely discounted when none of the 140 nor any of Dando's ex-boyfriends were found to be in Fulham on the day.
When asked if she had any stalkers, sister Judith said: "Not that I can remember in particular detail but I do know every now and again there were people she found.
"She wanted to be nice to everybody but she found it hard when they made her life difficult."
The Murder of Jill Dando is available on BBC iPlayer
