Matthew Locke, 38, formerly of Ware, was found guilty of four counts of first-degree murder in the slayings of Sara Bermudez, 38, Madison Bermudez, 8, James Bermudez, 6, and Michael Bermudez, 2, the Worcester County District Attorney's Office said.
Locke, a cousin of Moses Bermudez, committed the March 1, 2018, murders while Moses was out of town in California, authorities said.
The trial lasted four weeks and included more than 1,000 pieces of evidence and testimony from 70 witnesses. The jury deliberated for only 10 hours before convicting Locke.
Prosecutors argued during closing statements that Locke was high on cocaine at the time of the murders and broke into the house looking for money. He then attempted to destroy evidence by pouring diesel fuel throughout the home and setting it on fire.
However, the fire extinguished itself before destroying the house.
Police testified that Locke brutally killed all four victims. Both Sara Bermudez and her oldest daughter, Madison, were sexually assaulted with a knife and repeatedly stabbed. The two boys were stabbed so violently that the blade penetrated through their bodies. The youngest child, Michael, was found severely burned by the fire.
Defense attorneys argued that Locke lacked the intelligence and competence to carry out such a crime without leaving substantial evidence.
Forensic experts testified that Locke's DNA was found on the external genital areas of both Sara and Madison. Additionally, multiple inmates testified that Locke had admitted to his involvement in the murders.
Locke faces life in prison without the possibility of parole when he is sentenced. A sentencing date has not yet been set.
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