Paul Massey and John Kinsella: Gangland murders arrest
Another man has been held on suspicion of the murders of an underworld "Mr Big" and a gangland enforcer.
Paul Massey, 55, was shot as he got out of a car in 2015 while John Kinsella was killed on 5 May.
On Saturday, Mark Fellows, 37, appeared in court charged with their murders and the attempted murder of Kinsella's partner.
Later in the day, police arrested a 35-year-old man who remains in custody for questioning.
Fellows has been remanded in custody and is due to appear at Liverpool Crown Court on 5 June.
Massey, 55, was shot five times as he got out of a car outside his home on 26 July 2015.
A security boss and businessman, he was a convicted criminal once branded "Mr Big".
Kinsella died after being shot by a man on a bicycle while he was walking and his partner were walking their dog on 5 May.
She was shot as she fled the scene at the St Helens Linkway near the M62 in Merseyside.
Kinsella had been described as a mob fixer who once stopped a gangster threatening former Liverpool footballer Steven Gerrard.
Five other people arrested this week have been released under investigation.
Det Ch Insp Carl Jones, of Greater Manchester Police, said: "This has been a busy week of operational activity and last night we made a further arrest in connection with the murders of Paul Massey and John Kinsella.
"That man remains in custody for questioning and both victims' families have been informed."
The force has been working alongside Merseyside Police who said their inquiries "allowed us to establish a number of positive leads".