There's one big problem with this crucial piece of evidence in favour of Steven Avery on 'Making a Murderer'

One of the strongest pieces of trial evidence in favour of “Making a Murderer” subject Steven Avery was the vial of his blood from a previous conviction that appeared to have been tampered with. But new information makes that piece look a lot weaker. reports that court papers from Avery’s appeal show prison nurse Marlene Kraintz was set to testify in Avery’s trial for the 2005 murder of Teresa Halbach that she punctured a hole in the test tube of Avery’s blood, and in fact such holes are commonplace, because that’s often how the blood gets put in the tube in the first place.

Avery’s defence team, Dean Strang and Jerry Buting, discovered the hole in the test tube’s stopper. They believed it was proof that the Manitowoc County Sheriff’s Department had tampered with the evidence and withdrew blood from the tube. The theory supposed that blood was later smeared in the victim’s car to incriminate Avery.

If Kraintz had testified, it would have gone a long way to discrediting the theory and Avery’s perceived innocence. According, she would have explained that it’s common practice to fill a test tube via syringe. But she wasn’t called to the stand.

“We did not believe that the defence had raised the issue significantly enough [at trial], claiming that there was any tampering done to the blood vial,” former prosecutor Ken Kratz told the site. “Although the documentary suggests that the hole in the vial of blood was significant, everybody at the time knew and certainly the filmmakers had to know that the hole in the vial was put there by the nurse who drew the blood.”

In addition to Kraintz, the website interviewed two other experts who also said that it’s common practice to fill a test tube in that manner.

“Making a Murderer” also shows that the vial was supposed to be in a sealed box. But when the prosecution discovered it, the seal had been broken. Manitowoc County DA E. James Fitzgerald said that he opened the box after both sides were given permission to study the evidence from Avery’s previous trial.

For some, that might seem enough to strike down the planting argument by the defence. But the site points out that just because Kraintz would have testified to making the hole, there’s no way to know if someone else extracted blood from the tube through the same hole.

NOW WATCH: The lawyer from ‘Making A Murderer’ describes what’s wrong with America’s criminal justice system

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