A homeless father arrested for sleeping in an Adelaide CBD stairwell has had the charges against him dropped after a high-profile barrister stepped in to help.

David Evans, 57, spent Christmas Day behind bars after police arrested him the night before.

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He had been found sleeping rough in the stairwell of an indoor carpark on Frome St for two nights in a row.

On Christmas Eve he was charged with trespassing and given a city exclusion order.

Due to face court three days later, Evans contacted Mary Shaw KC, one of South Australia’s most accomplished barristers.

Shaw was the lead defence lawyer in the Snowtown case, Australia’s worst serial murder in which 12 people were killed between 1992 and 1999, with most of the bodies stored in barrels filled with acid.

Evans and Shaw had crossed paths 18 years ago when Shaw was a judge and Evans appeared in court for possessing heroin.

He had been using the drug to help numb the pain of a facial injury he had suffered in a car accident.

Shaw ordered Evans be seen by a doctor so he could be prescribed the correct medication to help with his pain.

The 57-year-old father later wrote to Shaw, thanking her for her humanity and kindness.

David Evans, 57, and top barrister Mary Shaw KC. Credit: 7NEWS
Evans had been found sleeping in a stairwell inside an indoor carpark in Adelaide’s CBD. Credit: 7NEWS

“It put me back together with my family, with my son,” Evans told 7NEWS.

“He was only a little fella at the time, 5 or 6, and it meant the world to him.”

Thanks to Shaw’s help, the charges against Evan were dropped on Wednesday morning.

Appearing outside court, Shaw said she wanted to make an example of Evans’ case because she feared homelessness was being criminalised.

She will lobby the SA Attorney-General to find alternative ways police can deal with people who find themselves sleeping rough.

“Our services could be better spent on those who really do deserve to be in prison, not the people like Mr Evans,” Shaw said.

– With reporting by Hayden Nelson