The former chief forensic scientist in the Stephen Lawrence murder investigation has told the Old Bailey he was concerned that crucial evidence had become contaminated.
Adrian Wain said that by the late 1990s sellotape used to seal bags of clothing had become ineffective.
Prosecutors say evidence on the clothes of Gary Dobson, 36, and David Norris, 35 links them to the 1993 killing.
Mr Dobson and Mr Norris deny murder and say police contaminated the evidence.
Mr Wain told the jury he had warned police in July 2001 that the sacks and sticky tape used to seal exhibits could degrade and therefore let in fibres or hairs.
He said: "I was aware that items had been in and out of the laboratory. I didn't have control of them outside the laboratory. I didn't know whether they'd been in the same location outside the laboratory.
"I knew that the packaging was deteriorating, I knew that the seals were deteriorating. I had concerns about contamination.",,read more