In 2013, Haigh was 24-years-old and working as a public policy manager for the insurance company Aviva.
Following reports by Sky and The Times on Thursday, Haigh issued a statement, explaining she made a police report after a "terrifying" mugging in London.
She said she reported the phone as one of a number of items she believed had been stolen, and was issued with a new work phone.
Some time later, she discovered the handset was still in her house, and she switched it on, which "triggered police attention" and she was called in for questioning.
"My solicitor advised me not to comment during that interview and I regret following that advice," she said, and the matter was sent to magistrates.
Haigh said she pleaded guilty to making a false report to police at a magistrates' court, six months before becoming an MP in the 2015 election, and received a discharge - the "lowest possible outcome".
I'm surprised she's resigning over something so minor tbh.