Standing at the bottom of the pitch-black staircase with an automatic rifle slung over his shoulder, Sgt. Joseph Chavalia felt a hand grab the back of his thigh.
It was a signal to move forward, he would later testify.
The quick tug told him that fellow SWAT officer Ronald Holman was right behind. Together they climbed the stairs into the most vulnerable spot in the house. A place where they would be easy targets if anyone in one of the three upstairs bedrooms had a gun.
With each step, Holman and Chavalia said they screamed: "Police! Search Warrant! Get Down!"
Chavalia's eyes were just above the second-story floor when he swung around toward a bedroom light. He said he saw a shadow move behind the door. Then back out again. "Police department," he yelled.
Gunshots rang out. He flinched and the silhouette popped back out. He could tell it was an adult. Then more gunfire, he said. "There was no doubt in my mind it was coming from that room," he said.
Chavalia braced the rifle against his chest and fired three rounds, the bullets blasting through a wooden railing and into the bedroom where Tarika Wilson held her one-year-old son. Wilson, 26, was dead almost immediately. The boy also was hit, but alive.
It turned out that the gunfire that Chavalia thought was directed at him was coming from downstairs - where other officers shot two charging pit bulls - and not from the unarmed black woman in that bedroom.
Whether Chavalia, a white 31-year police veteran, is convicted in Wilson's death will come down to whether jurors believe his testimony that he thought his life was in danger. They'll decide whether he recklessly fired at someone he couldn't see during a drug raid in January.
Jurors could begin deciding the case Monday after hearing from the final witnesses in the trial that began last week.
Chavalia has pleaded not guilty to misdemeanor counts of negligent homicide and negligent assault. If convicted of both, he faces up to eight months in jail.
The shooting sparked outrage in a city where one in four residents is black. It exposed a mistrust of police among black residents and led to much discussion about race relations and what happens to cities when manufacturing jobs move out and drugs move in.
The northwest Ohio city has been simmering, as more than six months passed before much was known about what happened inside Wilson's rental home that night.
Testimony last week from Chavalia and other SWAT team members revealed that there was plenty of tension leading up to the raid.
The officers had been warned that the suspected drug dealer they were looking for, Wilson's boyfriend Anthony Terry, could be dangerous.
They were warned that he once tried to wrestle a gun away from an officer. They knew he might have pit bulls in the house. And they were told there were toys on the house's front porch, an indication that children might be inside.
The team of SWAT members said nothing as they rode in a van to the house. As they got closer, their leader started a count down: "30 seconds out. 20 seconds out. 10 seconds out."
Two officers with a battering ram and a steel bar pulled the front door open. Chavalia was the second one inside the completely dark downstairs. Shouts of "Police! Get Down! Search Warrant!" rang out.
Most of the officers stayed on the first floor. Chavalia and Holman went upstairs.
What happened next left a mother of six dead and a city shaken.