Former Environmental Science and Research scientist Peter Cropp told the Bain murder trial in Christchurch today that one of David Bain's socks he tested had blood from siblings Stephen or Laniet Bain on it.

No results were available from the other sock, he told the 18th day of the Bain murder retrial before Justice Graham Panckhurst and a jury in the High Court at Christchurch.

He was not able to tell which foot each sock came off because they were in a packet as a pair.

Bain has denied shooting dead five members of his family with a .22-calibre rifle at their family home in 1994.

Dr Cropp said the four blood samples taken off the rifle's silencer, barrel, wood and scope could have come from sister Laniet, brother Stephen, or accused David Bain.

The black shorts David was wearing had a small stain on the crotch. Dr Cropp said it was blood from either mother Margaret, sisters Arawa or Laniet, or Stephen.

He tested the T-shirt taken off Stephen's body and found that the blood on it was Stephen's but noticed a honeycomb pattern of blood on the right sleeve which, he said, would have come off an open-weave type of garment with blood on it.

The track-pants worn by father Robin Bain had four spots tested and the results showed that they were all his own blood.

The blood on the white cotton gloves found under the bed in Stephen's room could only have come from Stephen or Laniet.

Dr Cropp is the fourth forensic scientist of eight to be called and his evidence will continue tomorrow.