Police are investigating a mile long trail of suspected human blood discovered in Hull.
The blood, which stretches for more than a mile from St Andrew's Docks to parts of Hessle Road, was discovered by a passerby who was fishing off the docks on Thursday.
The fisherman alerted police shortly before 11am that day.
Humberside Police say they are concerned by the "substantial" amount of blood discovered in the area.
The force said extensive enquiries, including a search of the river bank by Air Sea Rescue, have been undertaken but have so far failed to identify a victim. Samples of the blood have been sent away for DNA analysis.
Detective Inspector Joanne Roe said: "Due to the substantial amount of blood found we believe the person may have sustained a severe injury of some description and may be in need of medical attention."
Anyone with information is asked to contact police on the non-emergency number 101.Reuse content