Officials say Prince George's County Detective and Delaware County native Jacai Colson was killed March 13 by a fellow officer returning fire after a man shot at a police station in Landover.
Police say the officer didn't recognize Colson but feared for his life.
Colson was pronounced dead at the hospital, just a few days shy of his 29th birthday.
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At a funeral service Friday in Upper Marlboro, Maryland Gov. Larry Hogan and County Executive Rushern Baker praised the Pennsylvania native's bravery and dedication to duty, while friends and family spoke of his big heart.
A wounded suspect, 22-year-old Michael Ford, was arrested and faces more than two dozen charges, including second-degree murder.
Police have described the incident as a suicide attempt by Ford. Police say his two brothers helped; they, too, are charged.
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Friday's funeral for 28-year-old Colson got underway at 11 a.m. at First Baptist Church of Glenarden in Upper Marlboro. It was open to the public.
Colson was a four-year department veteran.
Before he served as an undercover narcotics officer for the Prince George's County Police Department, the Boothwyn native was the quarterback for Chichester High School, a class officer, and a member of their basketball squad.
"Jacai was the greatest grandson you could ever have. He was kind, courteous, and he was just wonderful and I'm going to miss him a lot," Jacai's grandmother said.
"You know when the phone rings at night, you always figure that something bad had happened and she told me that he had got killed," cousin John Walker said.
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Colson died doing his dream job, one inspired by his grandfather, who was a longtime Upper Chichester police officer.
"He was a very sharp young man, very sharp," grandfather James Colson said.
Chichester School Board President Ruth Ann Baiocco has known Colson's family for years; one her sons played football with him.
"He was your Chi-pride. He was the quarterback. He was liked by everyone. He was my youngest son's camp counselor," Baiocco said.
Colson graduated in 2005 then went on to Randolph Macon College before later coming a police officer, like his grandfather.
Colson's parents still live in the Philadelphia area. They were given a police escort to Maryland.