A second walker has been killed by cows in less than two weeks.
Malcolm Flynn was walking the Pennine Way in Northumberland when the herd stampeded.
Mr Flynn, 72, was fatally injured and died at the scene.
Detective Chief Inspector Jane Fairlamb, of Northumbria Police, said:
“Our investigation is very much ongoing, and we have already spoken to a number of witnesses.
“However, we are still trying to trace a number of people who were in the area at the time who we haven’t yet spoken to, and think could greatly assist our inquiries.”
School teacher David Clark was also killed by cows while walking his dog in Richmond, North Yorkshire.
Ninety-eight people have been killed by cows in the last 20 years.
The Health and Safety Executive said 22 were members of the public and 76 farm workers.
The National Farmers Union (NFU) recommends walkers keep themselves safe by following the country code.
Cattle could become aggressive if they felt threatened, particularly if they have calves with them.
An NFU spokesperson said:
“If walking with a dog it [the code] recommends keeping dogs on a lead and under close control around farm animals and horses, but to release them if threatened or chased by livestock.”