A second man was arrested on suspicion of murder after police were called to Runcorn Bridge over the weekend.
Police were called to reports of a man parking his car and 'acting suspiciously' between 8.30pm and 9pm on the Silver Jubilee Bridge in Runcorn, on Saturday, February 12.
As a result, detectives visited a number of houses in St Helens and arrested a 43 year old man on suspicion of murder.
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He was taken into custody to be interviewed and has since been released under investigation.
After further investigation, a 38 year old man, of no fixed address, was arrested in the early hours of Monday, February 14, in Cheshire.
He remains in police custody in Merseyside where he awaits interview.
Police remain at the scene of Runcorn Bridge today with an underwater search unit has been stationed on Collier Street.
No body has been found and police are 'keeping an open mind' about what has happened.
Detectives are appealing for witnesses and dashcam footage from Saturday night.
Detective Superintendent Steve Reardon said: "We are making progress with this investigation and are keeping an open mind about what has happened.
"I want to make it clear that our officers have not located anyone injured or deceased during the course of this investigation, but the behaviour of the man on the bridge and comments he made were concerning.
"As we work alongside colleagues at Cheshire Police to get a full understanding of the circumstances, and searches continue, we are still very keen to hear from anyone who crossed the bridge between 8.30-9pm on Saturday to get in touch.
"Any information you have, and particularly any dashcam footage you may provide, could prove vital."
Anyone with information on this incident is asked to contact Merseyside Police social media desk via Twitter @MerPolCC or Facebook Merseyside Police CC with reference 22000106196.
Merseyside Police are requesting for anyone using the Bridge at this time with dashcam footage to upload it using the following link:
__ https://unitedkingdom1cpp-portal.digital-policing.co.uk/merseyside/appeal/silver-jubilee-bridge-enquiries
You can also call 101 or contact the independent charity Crimestoppers anonymously, on 0800 555 111 or via their online form at: https://crimestoppers-uk.org/give-information/give-information
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