Several dozen spots of suspected blood were marked by forensic scientists combing Jeffery Trevino and Kira Steger's St. Paul home for possible signs of a murder, but not all the samples were thoroughly tested to determine their makeup and origin, scientists testified Tuesday.
The difference in how some suspected blood evidence was treated compared with others stoked the most tension yet between Ramsey County prosecutors who are trying to prove that Trevino killed his wife in a jealous rage and defense attorney John Conard, who at one point handed a textbook to a scientist on the witness stand when she couldn't answer his question.
"You want to give that a read?" Conard asked Lindsey Garfield, a scientist at the Minnesota Bureau of Criminal Apprehension.
Trevino, 39, faces two counts of second-degree murder in Ramsey County District Court in the death of Steger, 30, who was last seen alive on Feb. 21 and whose body was recovered on May 8 from the Mississippi River.
Conard has long waited to pounce on the forensic evidence prosecutors are levying against his client. Prosecutors wrongly describe the residence as containing "copious amounts" of blood evidence, Conard has said, when "less than a thimble" of Steger's blood was found there.
Garfield's statements came during the longest testimony of the 36 witnesses who have spoken so far. She took the witness stand for nearly six hours on Tuesday, the fourth day of testimony.
Garfield processed much of the alleged blood evidence recovered Feb. 25 and 26 from Trevino and Steger's rental home in the 500 block of Iowa Avenue E., and tested several locations with "presumptive" tests. Several spots identified in the master bedroom, hall, kitchen and bathroom tested positive for blood with the presumptive tests, which are not definitive without further testing, she testified.
Garfield said many of the spots were visible to the naked eye and were dark-colored, while others only showed up after the chemical luminol was applied to surfaces in the home. The chemical glows a neon blue in the dark when it comes into contact with blood, metal and other substances.