The investigation into what caused the Virgin Galactic test flight to crash could take as long as 12 months, lead investigator Chris Hart has said.
Mr Hart, who is acting head of the National Transportation Safety Board, also told reporters that his team would interview injured co-pilot Peter Siebold when he was ready.
Virgin Galactic has moved to defend its safety record and denied reports the firm ignored warnings ahead of a test flight crash in which one pilot died and another was seriously injured. It had been claimed concerns were raised about the safety of their project which aims to send tourists to space.
In a statement Sir Richard Branson's spaceflight company refuted any allegations they had ignored safety warnings.
"At Virgin Galactic, we are dedicated to opening the space frontier, while keeping safety as our 'North Star'. This has guided every decision we have made over the past decade, and any suggestion to the contrary is categorically untrue," the company said.
Engineer Geoff Daly has filed complaints with several American government agencies over the use of nitrous oxide to power the spaceship's engine.
Faced with a five-mile debris trail and masses of technical data, the team investigating the crash of SpaceShipTwo have their work cut out.
The loss is a tragedy for this small tight-knit team that dreams of making the trip into space accessible to travellers not just astronauts.