The death of a skydiver whose parachute failed to open over an airfield in North Lincolnshire is now being treated as murder. Stephen Hilder, who was 20, fell 13,000 feet to his death while he was taking part in a jump, at Hilbaldstow Airfield, on Friday.
Detective Superintendent Colin Andrews, who is leading the investigation, said parts of Mr Hilder's kit had been tampered with, so neither his main parachute nor his reserve could open.
He said "It is an absolute fact that both parachutes were deliberately tampered with and on the basis of that we have to strongly suspect that murder was the motive."
Mr Hilder, an officer cadet who had completed more than 200 parachute jumps, was found dead in a cornfield.
His family, from Hereford, paid tribute to a "wonderful son and brother."
Humberside Police carried out forensic tests on the parachute pack used by Mr Hilder and say the cord which deployed the main chute and the strapping to the reserve chute had been cut.
DS Andrews said: "We are entirely satisfied that Stephen's parachute was deliberately tampered with and what we need to find out is who did that and for what reason."
He said Mr Hilder was an experienced skydiver who was safety conscious.
"It is a tragic waste of a young man with a bright and promising future and it is a particularly horrendous way to die," he said.
The parachute equipment had been checked on Wednesday - the day the jump had originally been due to take place - and "stored in good working order".
Mr Andrews said the parachute was kept in a store that was locked overnight but was left open in the day.
Police say a fancy dress party was held at Hiblestow Airfield on the evening of 3 July which was attended by a number of people, including Mr Hilder.
Many of the people who attended took video footage and photographs of the party and police are appealing for them to get in contact.
They are also examining video footage of the actual fall which was filmed by people at the site.
Mr Hilder was one of eight people who took part in the jump but no one else was injured.
The airfield has re-started parachute jumping and security has been reviewed.
Meanwhile, a skydiving expert said it would be relatively easy to sabotage a parachute jump.
Dave Hickling, chief instructor with the British Parachute School based at Langar Airfield near Nottingham, said: "You don't need a lot of knowledge to cut things.
"Once you have been on a basic parachute course and you have seen how the parachute deploys, you would have enough knowledge."
In a statement Mr Hilder's family said: "He was a wonderful son and brother, whose place in his very close-knit family will never be filled."
skydiving had "quickly become a total passion" for him after he took it up at Bristol University, they said.
He continued skydiving when he transferred to the Royal Military College of Science at Shrivenham, Oxfordshire, last year, where he helped revitalise the college's skydiving club.
"He made over 200 jumps in the UK, France and South Africa, including freefall and formation diving and his absolute love for the sport never faded," they said.
Mr Hilder was born in Hereford and went to school there before studying for his A-levels at Welbeck College.
The statement continued: "Throughout his time with the Army he kept his love of theatre and music.
"He was a talented percussionist and amateur actor, who loved reading and listening to rock music.
"Steve had a tremendous sense of humour and made friends wherever he went."
A post mortem found Mr Hilder died of multiple injuries.