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Walnut Creek Police Department
Friday April 28th, 2017 :: 05:31 p.m. PDT


Walnut Creek Homicide Suspect Arrested

Chief of Police Thomas Chaplin

April 28, 2017

For Immediate Release


DATE / TIME OCCURRED: April 27, 2017 at 1:30 pm

LOCATION: 1900 block of 1st Avenue, Walnut Creek


VICTIM: Roselyn Policarpio, 47 year old female, with last known addresses in Martinez and Stockton.

SUSPECT: Gregory Prokopowicz, 38 years old, with last known addresses in Martinez and Walnut Creek. In-custody for PC 187: Homicide.


On today’s date, at approximately 11:30 AM, Central County SWAT (WCPD, SRPD, MPD, PHPD and BART) took over the event in Martinez from the Contra Costa County SWAT Team. Negotiators negotiated with Prokopowicz for approximately 90 minutes when he exited his vehicle to retrieve a water bottle from outside of his vehicle. SWAT operators directed him to keep his hands up and to surrender. Prokopowicz refused their orders, grabbed the water bottle and turned to run back to his vehicle. A 40 mm less than lethal sponge round was fired at him and struck him on his right rib cage area. Prokopowicz was able to get back into the vehicle and closed the door. Negotiators continued to negotiate with him and after approximately 90 more minutes were able to convince him to throw his firearm out the window and later a knife. Prokopowicz armed himself with another knife and refused to throw it out the window and refused to come out of the vehicle. SWAT deployed three rounds of tear gas into the vehicle and within seconds Prokopowicz came out of the vehicle and surrendered. Prokopowicz was arrested at 2:11 PM for homicide.

He sustained a minor injury to his ribs from the less than lethal round. He was transported to a local hospital for treatment and release. He will then be transported to the Martinez Detention Facility. No other persons were injured during the standoff. The standoff lasted approximately 19 hours.

Special thanks to the Contra Costa County Office of the Sheriff, California Highway Patrol, Contra Costa County Fire Protection District, and the Walnut Creek and Martinez communities for all of their support through this event.

If anyone has information regarding this crime please call Walnut Creek Police Department immediately at 925-935-6400 or Detective Greg Leonard at 925-256-3523. The new PIO will be Lieutenant Tracie Reese;


Press Release Prepared By: Lieutenant Tom Cashion 925-943-5880

Walnut Creek Police Department
1666 N Main St
Walnut Creek, CA 94596

Emergency: 9-1-1
Non-emergencies: 925-943-5844

Lieutenant Tom Cashion

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