Detectives continue to question a third person arrested over the escape of a murderer from custody.
A 25-year-old man from Norris Green, Liverpool, was detained on suspicion of perverting the course of justice after armed men freed Shaun Walmsley on Tuesday, police said.
Two people arrested on Thursday for allegedly assisting an offender have been released on bail pending further action.
Walmsley, 28, from Liverpool, went on the run when two men armed with a knife and a gun confronted prison officers guarding him at Aintree University Hospital during a visit from HMP Walton on Tuesday afternoon.
Merseyside Police are said to be joining up with forces overseas as well as in the UK as part of their search efforts for the killer.
A 27-year-old man and a 26-year-old woman at a property in Norris Green, Liverpool, on Thursday evening in connection with the escape.
Walmsley and the men fled in a gold Volvo with the registration number MW02 XHE, which detectives found in the Fazakerley area of Liverpool.
CCTV images have been released showing the moment the armed men threatened prison officers.
Detective Superintendent Natalie Perischine said: "The CCTV shows that the people involved in the actual incident were in a very close huddle and we know that although a gun and knife were used by the offenders, they were not blatantly on show to other people walking by.
"These witnesses may not have realised what was going on.
"They may have thought it looked a bit odd, but probably wouldn't have thought anything of it.
"We do know that the gold Volvo was blocking the rear of the car which was meant to take Walmsley back to prison, and this was making access to a roundabout at the hospital difficult and one delivery driver was forced to mount the kerb to get past."
The officer appealed for the public to look at the images and to contact the police with information.
"I would like to reiterate that Shaun Walmsley and the two others involved in the incident are dangerous individuals and we will be relentless in our pursuit of them," she added.
Walmsley was serving life with a minimum of 30 years for the murder of Anthony Duffy, 33, in May 2014.
Mr Duffy was lured to an address in Aintree and repeatedly stabbed and left for dead.
Anyone with information should contact police on 999 or Crimestoppers anonymously on 0800 555 111.