Retired Detroit firefighter Jeffrey Ziegler, 53, took the stand Thursday and told the court his wife was scared when a 14-year-old boy knocked on their door in April.
The teen, who is African American, missed the bus and says he went to Ziegler's house to ask for directions to school.
The couple says they thought the teen was trying to break in.
Surveillance video from the home caught what happened on the porch. Ziegler's wife says she went to call police. Ziegler allegedly got his gun from his office and was trying to protect his wife when he lost balance.
Ziegler said he regrets what happened, and if he could do anything different, he would have given the teen a ride, but the prosecutor said he was acting reckless.
Both sides will deliver closing arguments Friday morning.
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