The family of a man who died hours after he was arrested said he was "such a loving person".
Anthony Edwards, 37, "suffered a medical episode" and was taken to hospital on Sunday, the force said.
Officers were called to Keir Hardie Avenue in Bootle at about 09:30 BST following "reports of a man behaving erratically in the street", and he was detained on suspicion of causing criminal damage, Merseyside Police said.
The case has been referred to the Independent Office for Police Conduct (IOPC) due to police contact before Mr Edwards was taken to hospital.
The force said inquiries into the incident "remain ongoing".
The family said: "Our beloved Anthony, such a loving person. Words cannot describe how devastated we are. Your friends and family will miss you dearly."
They added: "We ask for privacy at this time so we can grieve together."
