FORENSICS 178: SOLUTIONS COURTESY OF LIBS

This essay might be of special interest to writers of detective and mystery novels who would like to enrich their stories by providing their readers with a gift of extra details. It might also be of general interest to many other readers, especially those who are CSI and NCIS fans.

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Although the outcome of some criminal cases are decided by one crucial piece of evidence. many are based upon a combination of supporting pieces of evidence. Such a case was one involving a murder in Texas. A major factor was provided by a friend of the murderer to whom the latter had confessed. Supporting evidence was provided using a unique method that promises to be applicable in many other situations.

Moises Sandoval Mendoza had recently turned 21 when he strangled, stabbed and assaulted a 20-year-old mother and school acquaintance named Rachelle O’Neil Tollesone. Mr. Mendoza was a Mexican national living in Farmersville, Texas. Ms. Tollesone also lived in Farmersville At the time of the murder, Mr. Mendoza was awaiting trial for aggravated robbery with a deadly weapon. He was accused of having been involved in the commission of several robberies at gunpoint in Dallas. He had also been charged with misdemeanor assault for allegedly having attacked his own sister in the front yard of the Mendoza home.

According to court documents filed by police, Mendoza had hidden Ms. Tollesone’s body in brush behind his house, but, after having been questioned by police about her disappearance, he had moved it to a remote area and tried to remove her fingerprints by burning her body. Mr. Mendoza later revealed details of what he had done to a friend, Stacy Marie Garcia. Since the information she provided to authorities included details that could not have been known by anyone not somehow connected to the murder, a judge signed a warrant for Mr. Mendoza’s arrest.

Police and volunteers searched areas around Farmersville for Ms. Tellesone’s body, but it was ultimately discovered in another county by a man looking for arrowheads. A medical examiner was able to identify the burned body by comparing the body’s teeth with Ms. Tellesone’s dental records.

Although the information provided by Ms. Garcia was compelling, the sheriff’s office did not halt its investigation at this point. They contacted a dendrochronology expert with hopes of finding supporting evidence using annual tree rings in what appeared to be partially burned fireplace logs used to burn Ms. Tellesone’s body. Mr. Mendoza had been seen putting similar logs in a fireplace at a social gathering. Unfortunately, the expert found the logs to be of mesquite, a wood that grows so erratically that tree ring analysis would not provide dependable information.

Eventually, a physicist used a Laser Induced Breakdown Spectrometry (LIBS) technique to analyze logs from the scene where Ms. Tellesone’s body was burned and from those Mr. Mendoza had been seen putting in the fireplace. Trees extract metals and other trace elements from soil, and their presence reflects what metals and other elements reside in soil in their location. Using the LIBS technique, a strong, pulsed laser was focused onto a sample of the wood, breaking it down to form a plasma. As the plasma cooled, atoms of different elements in the sample emitted energy in the form of light. Each element emitted light having a unique wavelength. Each wavelength was used to identify a specific element. The intensity of emitted light was used to identify an associated element’s concentration. The information provided by the technique has been referred to as a chemical “fingerprint.”

Burned and unburned portions of the logs were specifically tested for the presence and concentrations of aluminum, calcium, carbon, iron, magnesium, manganese, nitrogen, silicon, sodium and titanium. The resulting spectra of the mineral contents of both burned and unburned portions of all the tested logs were found to be identical. That indicated they were all from a single tree or from trees in an immediate vicinity.

The combination of the testimony provided by Ms. Garcia and the LIBS data resulted in a death sentence for Mr. Mendoza.

ADDITIONAL INFORMATION:

Thirty-two US states have death penalties; eighteen do not. Six have abolished it during this century.

The term, dendrochronology, refers to the dating and study of annual growth rings in trees. It has often been used to discover ancient climate patterns.

Tree ring comparisons have had a place in forensics since at least 1932, when tree ring patterns in boards used to make a crude ladder were found to match rings in boards found in one Bruno Hauptmann’s attic. Hauptmann was believed to have used the ladder to gain entry to the Charles Lindbergh home to kidnap the Lindberghs’ 20-month-old son.

As an added bit of trivial nostalgia, the superintendent of the New Jersey State Police during the Lindbergh kidnapping affair was the father of the late General “Stormin Norman” Swartzkopf. Those readers alive during the 1930’s or who are fans of recordings of “Old Time Radio” programs might recall Stormin Norman’s father narrating a popular, true-crime radio program named “Gang Busters.”

2 comments to FORENSICS 178: SOLUTIONS COURTESY OF LIBS

  • Everything is recorded in a “log” somewhere. :-)

    Assuming the science behind all that an analysis is reliable and done impeccably, justice is served! Another wonderful presentation of yours, Amalgam, done with compelling flourishes, for which you have come to be known! Love your added related information in this format. Fascinating about the Lindbergh baby kidnapping and the role of timber analysis there. Was not alive in the 30s, but you know I’m a fan of old-time radio, and Gangbusters is often aired on Sirius radio. Thanks for yet another addition to this virtual encyclopedia you are accumulating (you write rings around trees).

  • Robert Jones

    Thank you.
    Amalgam

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