The BBC has been following the hearings about baby Elsa for nearly two years.
Elsa was left in a Boots shopping bag in January 2024, when she was less than an hour old.
She was found on the coldest night of the year, so hospital staff named her after the character in the Disney film Frozen.
In June 2024, the BBC revealed she was the third child abandoned by the same mother and father. Her name and those of her siblings have now been changed.
After widespread media coverage, police stepped up their enquiries to find her parents.
Working with the National Crime Agency, officers identified several hundred houses where they believed babies’ parents might have been living. They knocked on more than 100 doors, spoke to local residents and took DNA samples.
They also used the babies’ DNA to try to identify relatives right across the UK, who they traced and spoke to.
But despite these efforts, police have said the parents have still not been found.
Det Supt Lewis Basford said enquiries were “exhausted” but officers would “continue to review all information and intelligence made available to us”.
He urged anyone who “may be sitting on information” to contact the police.