Three men have appeared before magistrates charged with the manslaughter of the youngest Briton to reach the summit of Mount Everest.
Mr Matthews disappeared during a tour
Jonathan Tinker, Henry Todd and Michael Smith are accused of unlawfully killing Londoner Michael Matthews, 22, on the mountain in May, 1999.
Mr Matthews disappeared descending the mountain in a blizzard during a tour.
No one from Alpine Mountaineering Ltd, which is also accused of manslaughter, appeared at York Magistrates' Court.
Mr Tinker, of Bishopthorpe Road, York, Mr Todd, of Thamel, Kathmandu, Nepal, and Mr Smith, of Verbier, Switzerland, spoke only to confirm their names and addresses during the hearing.
All four defendants were ordered to appear at the Central Criminal Court in London on 6 June.
Mr Matthews, who was a financial dealer in the City of London, has been presumed dead since he went missing in the 100mph blizzard six years ago.
The prosecution has been brought by his 62-year-old father David, a millionaire property investor and former amateur racing driver.
At 5.5 miles (8.9 km) high, Mount Everest is the world's highest peak.