(WSB Radio) -- A former Cobb County police officer will spend the next four years in prison for his involvement in the drowning of a fellow police officer.

Former Cobb County police Sgt. Kenneth Reda, 38, was sentenced in a Cherokee County courtroom to four years in prison Thursday. That will be followed by nine years on probation.

"Don't worry baby. Be strong." Mouthed Reda's crying wife as he left the courtroom.

Reda pleaded guilty earlier this month to second degree homicide by vessel, tampering with evidence, violating the oath of a police officer and three counts of making false statements.

Reda was drunk when his boat clipped a pylon on Lake Allatoona April 22. The crash tossed his best friend, Sgt. Brent Stephens into the lake where he drowned.

"Brent was my best friend," Reda said. "I'm sorry to the family. I'm sorry to my friends. I'm sorry to my family."

"Saying you're sorry doesn't help. Whatever you say at this late date is too little, too late, Judge Frank Mills said.

Reda was with Stephens and Reda's lover, Shelly Powell were coming back from dinner at a lakeside restaurant April 22 when their boat crashed into a navigation marker in the water causing Stephens to fall out. The 35-year-old's body was found the next afternoon.

911 records show Reda waited about 90 minutes before reporting the accident. Reda initially told police that Stephens had jumped out of the boat. Reda and Powell, who were neighbors at the time, also removed beer bottles from the boat before Reda took Powell back to the shore, investigators said.

Powell originally told police she was not on the boat, but changed her story. Less than a week later, Reda and Powell were charged with making false statements and obstruction.

Reda said he insisted on taking Powell to shore because he didn't want anyone to know she was on the boat. He admitted he was concerned about saying his marriage.

"If it wasn't for trying to hide my relationship with her, this wouldn't be the way it is now. I'm sorry," Reda said.

"We were very good friends," said Brent Stephens widow Lori. "The lies that took place that night and the day after were sickening."

Brent Stephens also leaves behind a 4-year-old son and an 8-year-old daughter.

Missy Reda, Kenneth's wife, said she decided to stay with her husband even though she learned of the affair only through media accounts of the accident. She said she understood why he lied to investigators and rescuers called to Lake Allatoona late April 22.

"He was having an affair and doing his best not to get caught, she said.

The Stephens family said they are satisfied with the punishment, but had the judge to give Reda the maximum. He faced 24 years in prison, but the judge decided against punishing him as if it were a homicide since Reda was drunk.