A man found floating in a lake in Sandwell Valley earlier this week died of neck injuries, a post mortem has revealed.
Police received a 999 call just after 9am on Wednesday when staff at Dartmouth Park spotted someone in the water.
The local man is believed to be 41-year-old Jasbir Singh Bains, although formal identification is yet to take place.
Detective Chief Inspector Wayne Jones is leading the inquiry and is appealing for information from the public.
"The man's death is currently being treated as a murder investigation and we want to hear from anyone who was in or around Dartmouth Park early yesterday morning and may have seen anything," he said.
"We urge anyone who knows anything that can help our with our inquiry to come forward as soon as possible."