Iain Packer has been arrested in connection with the death of Ms Caldwell, whose body was found in woods in 2005.
A man has been arrested over the murder of Emma Caldwell, nearly 17 years after her body was found in woods in South Lanarkshire.
Iain Packer, 49, was arrested in connection with her death on Thursday morning.
Ms Caldwell had been a sex worker in Glasgow’s red-light district when she disappeared on 4 April 2005.
The 27-year-old’s body was found five weeks later, 40 miles away in woods near Roberton in South Lanarkshire.
The unsolved case was reopened in 2015 following consideration by senior lawyers in the Crown Office and campaigning by Emma’s mother Margaret.
Police Scotland said the arrest was made in the Glasgow area on Thursday following significant inquiries by detectives from the Major Investigation Team.
‘Complex investigation’
Senior Investigating Officer, Det Supt Graeme Mackie, said: “Police Scotland officers have undertaken a significant amount of work re-investigating all the circumstances surrounding Emma’s death following instruction from the lord advocate in 2015.”
He added: “This is a complex and challenging investigation and I would like to thank everyone involved for their efforts in getting us to this point of a man being arrested earlier today.
“Emma’s family, in particular her mother Margaret, have shown incredible resilience and determination since her death in 2005 and I would like to pay tribute to that today.
“We have remained in close contact with them during this investigation and officers have updated Margaret on this significant development.”
Solicitor Aamer Anwar read out a statement on behalf of Emma as he sat beside her mother Margaret at a media briefing following the arrest.
He said that Margaret and her family were “truly grateful to the detectives at Police Scotland and the Lord Advocate Dorothy Bain’s team who have worked tirelessly in reinvestigating the murder of Emma since we met with the then Lord Advocate in 2015”.
He added: “I also wish to pay tribute to Margaret Caldwell, a mother who through the love of a child has never given up in her struggle for justice.
“The investigation into Emma’s death continues and her family would urge anyone with information, no matter how insignificant they might think it is, to please come forward and speak to Police Scotland.”