Jason S. Miyares
Attorney General of Virginia

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Commonwealth of Virginia
Office of the Attorney General

Jason S. Miyares
Attorney General


202 North 9th Street
Richmond, Virginia 23219
FAX 804-786-1991
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For media inquiries only, contact:  
Victoria LaCivita
(804) 588-2021 
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Attorney General Miyares Announces Guilty Plea in First-Degree Murder Charge

Lawrenceville, VA – Attorney General Jason Miyares announced the successful prosecution of an inmate at Lawrenceville Correction Center by the Major Crimes and Emerging Threats Section. Bret Cook pleaded guilty today to the first-degree murder of Mark Grethen at the Lawrenceville Correctional Center in August of 2021. 

On August 3, 2021, Grethen was found unresponsive and fatally wounded in his prison cell at the Lawrenceville Correctional Center in Brunswick County, Virginia. A subsequent investigation of surveillance video and DNA analysis conclusively linked Cook to Grethen's murder.  

"Today's guilty plea to first-degree murder demonstrates my office's commitment to combating violent crimes in the Commonwealth, including those committed in Department of Corrections facilities. Today, justice was served," said Attorney General Miyares. 

Cook was previously convicted of malicious wounding, grand larceny, armed robbery, malicious assault, assault by an inmate on an employee, four counts of misdemeanor assault, eluding, and conspiracy/robbery with the use of a gun at the time of the attack. He is currently serving a 21-year sentence.

The Brunswick County Commonwealth's Attorney's Office asked the Office of the Attorney General to assist in prosecuting this case. This case reflects our office's dedication to facilitating partnerships with law enforcement agencies and Commonwealth's Attorney's Offices throughout the Commonwealth to benefit all Virginians.  

The Commonwealth made no agreement as to sentencing, which will occur on May 25, 2023. A conviction for first-degree murder carries a sentence of 20 years to life in prison. Chief Prosecutor Phil O. Figura prosecuted the case for the Commonwealth.