Merseyside Police has arrested two more people following an incident in Heswall on Sunday 14 May.
At around 8.45am, police received a report that a 41-year-old man had been found on Milner Road with a serious head injury. He remains in hospital in a critical but stable condition.
Following enquiries on 14 May, police arrested two men, aged 41 and 37, both from Heswall, on suspicion of section 18 wounding with intent.
Police have also now arrested a 41-year-old man from Heswall and a 43-year-old woman from Prenton on suspicion of section 18 wounding with intent.
All four people have been conditionally bailed pending further enquiries.
Detective Chief Inspector Matt Caton said, “Although we have made four arrests, we are still appealing for anyone with information to please come forward to assist us in this ongoing investigation.
“If you live on Milner Road and captured anything suspicious on CCTV or smart doorbell footage, then please get in touch. Also, if you live in the Heswall area and captured anything suspicious that you think could help our enquiries, let us know.”
If you have any information, please contact Merseyside Police via @MerPolCC on Twitter or Merseyside Police Contact Centre on Facebook, with reference 23000407499.
You can also pass information anonymously via Crimestoppers on 0800 555 111, or contact them via their online form at: https://crimestoppers-uk.org/give-information/give-information
Always call 999 if a crime is in progress.