A 59-year-old man has died while out looking for his son's stolen motorbike.
Police said the bike was taken from the garden of a house in Cave Lane, Leeds, on Thursday.
After checking CCTV footage the father and his 31-year-old son went searching separately for four suspects seen on the video footage taking the bike.
The son returned later to find his father collapsed in a nearby street. Police said they were not treating the death as suspicious.
Det Insp Richard Holmes said a 21-year-old man had been arrested on suspicion of theft.
"The family of the man who died are understandably distraught at his death in these circumstances and we are doing everything we can to support them," he said.
"At this stage there is nothing to suggest any suspicious circumstances in relation to his death but we are continuing to carry out enquiries and a post-mortem examination is due to take place."
Mr Holmes said the stolen motorbike had not been recovered.