A woman convicted of theft after pocketing a £20 note she found in a shop said police initially told her "not to worry" about speaking to them.
Nicole Bailey, from Stoke-on-Trent, said she did not think she had done anything wrong when she found the cash on the floor of a corner shop.
Three months later, she voluntarily attended a police station as a witness.
Staffordshire Police said she was offered the same rights as a person being interviewed under caution.
The media storm around the case has brought a mixture of sympathy and condemnation for the 23-year-old, and Ms Bailey said her life has been "turned upside down".
She said the legal action and subsequent attention had jeopardised her job and she "really wished she could turn back time".
"The whole process has been very upsetting and I wanted it put behind me as soon as possible," she said.
Ms Bailey visited the One Stop in Blurton and picked up the cash after it was dropped by a fellow customer.
Three months later she was asked to attend a police station.
She said she had no memory of finding the money and was initially told by police that nothing would happen.
Three weeks later, she was asked to go back to the police station where she was shown CCTV of the incident and accepted she took the money. She said she was again told not to worry about it.
It was only when she got a letter asking her to attend court she realised she needed legal advice, she said, and realised she was potentially guilty of theft.
When faced with the prospect of a trial and having to pay legal fees, she said, Ms Bailey instead decided to enter a guilty plea at her first appearance in front of magistrates.
Ms Bailey, of Highfield Drive, Blurton, was told to pay £20 compensation, a £20 victim surcharge and £135 in court costs.
Her solicitor, Jason Holt of Stevens Solicitors, said anyone could find themselves in her situation and added he was sure she would not have ended up in court if she had sought advice from the start.
But Ch Insp Karen Stevenson, from Stoke South local policing team, said: "When individuals are interviewed voluntarily, they are offered the same rights as a person interviewed under caution.
"Anyone who declines this does so as their personal choice. In some specific circumstances, ordinarily, we can offer an out-of-court disposal if the person admits to the offence."
Correction 2 March 2017: An earlier version of this story contained an image of the wrong shop. This has now been amended.
- 1 March 2017