With her murder trial set to begin this week, Sandra Melgar’s defense is building an environment of uncertainty surrounding the investigation into the murder of her husband of 32 years for the jury.

Presenting evidence they call critical and ignored, Melgar’s attorneys say their client is innocent.

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Another pieces of evidence includes a bloody fingerprint on the safe located where Melgar’s husband Jaime was discovered.

Friends discovered him bound and stabbed to death in a closet of the couple’s home in December 2012, coincidentally further on the anniversary of their wedding.

Sandra was found tied up, but unharmed, in a separate closet.

The bloody fingerprint, which appears to support Sandra’s story of a home invasion, was never tested for DNA or latent prints.

Over the five years since the crime, the bloody print was lost from the evidence collected at the scene.

“What appears to be a bloody finger or thumb print was observed by (Crime Scene Unit) investigators and homicide detectives during the investigation of the handle of a safe that was located in the master bedroom closet where the body of the deceased was found,” the defense motion alleges. “Inexplicably, no examination was conducted for latent prints or the presence of DNA despite the fact that fingerprint ridges and grooves are easily observed on photographic evidence of the handle.”

The defense further claims the bloody fingerprint is among several pieces of evidence improperly handled, examined and tested, which, if investigated properly, they say will show Sandra innocence.

Despite repeated requests from Sandra’s defense, the evidence was never thoroughly tested.

Based on court documents, Sandra’s attorneys appear to be arguing the Harris County Sheriff’s Office decided early in the investigation the home invasion was staged, so it was later ignored as evidence not supportive of this theory.

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In court documents, the defense points to former homicide investigator Shawn Carrizal’s forced resignation for backdating search warrants as support for their claims.

They say, when Carrizal left the job, evidence in Sandra’s case was found untested in a filing cabinet.

This was two years after the crime.

The jury will have some questions for the Harris County Sheriff’s Office after Sandra Melgar’s defense team presents its case on faulty, untested evidence AP Photo/David J. Phillip