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Former School Superintendent Charged In Tyrrell Double Homicide (PC STATEMENT ATTACHED):

Mark Porter (mug shot GCSO)

By Kathee Baird

Springfield, Mo.- A former school superintendent for the Mountain Grove school district has been arrested in connection to a double homicide.

Mark Edward Porter, 53, has been charged with two counts of first-degree murder for the deaths of Jan and Gary Tyrell.  The Tyrells were found murdered  in their Greenbrier Avenue home in May. Until today, authorities had not released a cause of death in the couple’s murders and have been very tight lipped about their investigation.

Jessica Tyrrell called police on May 1st and asked them to conduct a well being check at her parents home in southeast Springfield after not receiving a routine goodnight text from her father the night before.  She told authorities that she last spoke to her mother the previous evening and that her parents were not answering their phones or responding to text messages.

 An officer went to the home around noon and found it secure.  Jessica Tyrell called authorities again about 7:00 p.m. after arriving at the home and asked an officer to accompany her inside “because she was afraid something had happened to her parents and she did not want to enter the residence.”

When officers entered the residence they found the couple dead in separate parts of the house.  An inside out latex glove was recovered near Jan Tyrrell’s body, according to court documents.   Investigators concluded that the Tyrrells knew their killer as there was no forced entry into the house which "was furnished with very high dollar items."

Authorities say a wall-in safe in the garage of the home “had scratch marks on the door….as if someone tried to break into the safe.” 

During interviews with the Tyrrells family members investigators learned that Mark Porter was a “very” close  friend of Gary’s who had recently asked Tyrrell to loan him $250,000.  Tyrrell did not loan Porter the money, however, family members noted that “he was one of  the few people allowed into the Tyrrell home.”

Investigators discovered several handwritten pages of notes about the face value of silver coins, which Gary Tyrrell collected and traded, with an estimated face value of $1,336.00 with an estimated resale value of $22,000.  According to the probable cause statement, Mark Porter sold silver coins with a face value of $1,321.00 and received $18, 531.40.  

When detectives interviewed Porter he told them he was supposed to meet Gary Tyrrell at McDonald’s on Battlefield Road on April 30th after Tyrrell taught a class at the Executive Center on Battlefield Road for William Woods University.  Porter said the class was to conclude around 9:30 p.m. but he left the restaurant around 8:30 p.m. after Tyrrell did not show up.  

Porter said he then went to the Tyrrell home where he “was unable to contact anyone at the house.”  He said he then returned to his office at IBM and worked until sometime between 9:30 and 10:00 p.m.  

A student of Tyrrells told detectives that he last saw Mr. Tyrrell when his class concluded around 7:00 p.m.

The case took a turn after an undercover detective recovered a coffee cup that Porter threw in the trash.  The DNA on the coffee cup matched a DNA profile the state crime lab developed from the latex glove recovered at the crime scene.

 Charging documents released today state that Jan Tyrrell died of blunt force trauma to the head (search warrant returns indicate investigators believe a rare engraved Walrus tusk was used to beat Mrs. Tyrrell) and Gary Tyrrell was shot twice in the head.  

Tyrrell home (courtesy Springfield News Leader)

With the absence of any information and case updates, many in the community expressed living in fear since the double homicide.  The  Tyrrells were considered by all who knew them to be quiet and kind, and not the type to have any enemies.

Gary and Jan Tyrrell

Porter was superintendent in Mountain Grove from 2003 – 2005 and retired as a superintendent from the Wright City School District in suburban St. Louis in 2008 and according to sources was a principal in Reeds Spring at one time.  

Gary Tyrrell was a longtime teacher, principal and administrator in Mountain Grove and taught at area colleges.  Jan Tyrrell was an Avon salesperson and an advocate for the elderly.