Diluted blood in drowning victims makes bruising look worse - explaining why tiny needle pricks in the crooks of Sarah Widmer's arms caused large bruises, a world-renowned death investigator testified Monday in the Ryan Widmer murder retrial.

Dr. Werner U. Spitz also testified that extensive bleeding around Sarah Widmer's neck and throat - which the county coroner blamed on blunt force or compression - actually was caused by paramedics' needle insertions in her neck.

He also testified that bleeding in the upper chest, around the area of the fourth rib, could have been caused by chest compressions that were applied in attempts to revive Sarah Widmer.

Spitz explained that, in drowning victims, the salty blood attracts non-salty water. As a result, the blood is diluted and is flowing at an increased volume with greater pressure through the blood vessels.