The husband's story seems solid, and so investigators begin searching for other suspects. They might have looked for a long time had it not been for a bloodstain analyst that the prosecutor's office brought in to look at the evidence. Upon examination of that section of wall where the husband's hand swipe was, he observed something strange, something that had been missed by the other investigators. The wall did not have two bloodstain patterns--it actually had three. Blood droplets spattered on the wall during the beating had been smeared by the hand and what are called "skeleton" stains were left. These stains have a ring of dried blood around the outside, but are clear in the center where the still-liquid blood had been wiped away. This was certainly consistent with the husband's story of why his fingerprints are on the wall. However, it does mean that the husband was there not too long after the attack took place, because the blood droplets were not totally dried.
The Missing Piece
Then the investigator startled everyone by announcing that the husband was there during the beating. On the surface of the swipe pattern was additional blood spatter, and these droplets were intact, not skeletons. The only conclusion was that they had occurred after the hand swipe was made, and that means that the husband was present before the end of the beating. But the attacker was left-handed and the husband right-handed. While this new evidence did not make him the attacker, per se, it did place him there at the time of the crime.
Renewed investigation revealed that the husband and a male co-worker were having an affair, and that they had conspired to kill the wife. Both were eventually arrested and convicted of the murder of the wife. If this blood evidence had not been accurately detected, the husband and his accomplice might have gotten away with murder.