His wrists handcuffed behind him, Neal appears to be resisting a jailer who holds him under his right arm and Knisley who has him by the left arm. As they half-carry, half-pull him toward the doorway, his knees and lower legs drag along the floor.

Reaching the doorway, they momentarily jam together three abreast and the jailer slightly trips over the raised threshold, his left hand at Neal’s back inadvertently pushing Neal to the floor with the forward force of his stumble.

From a prone position on the floor, Neal turns his head toward the jailer crouched over him on his right. The jailer moves his right leg reflexively back and away from Neal’s face.

Knisley then leans over from behind Neal and delivers a blow to the right side of his face with the heel of his open right hand. The left side of Neal’s head bounces off the hard jail floor in reaction. A pool of blood slowly forms beneath his face.

Knisley places a hand on the right side of Neal’s head as if holding it toward the floor for a second or two. He then steps to the front of Neal and leans down into his face, as if telling him something, even as another police officer and female jail staff member enter the room and assist in taking the prisoner back out of the camera’s view toward a cell.

Neal was under arrest at the time on probable-cause charges of felony assault on an officer and numerous related misdemeanors. Cpl. Chuck Niess, of the Police Department, told the Globe that Officer Trevor Duncan tried to stop a car Neal was driving about 1 a.m. on April 20 in the 200 block of West Fifth Street for blocking the street. Neal drove up onto a curb and stopped, Niess said.

As Duncan prepared to get out of the vehicle and make contact with the driver, Neal allegedly put the car in reverse and rammed Duncan’s patrol car. He then reportedly drove forward into a pole.

The officer and Neal both got out of their vehicles at that point and Neal started toward Duncan, Niess said. The officer commanded him to stop, but he did not comply, Niess said. Duncan then attempted to use a Taser gun on him, but it failed when one of the prongs did not make contact with him.

But it stopped Neal’s approach, and Duncan thought that he might begin to comply, Niess said. But when he went up to Neal to gain control of him, he pulled away and started walking away, prompting a second use of Duncan’s Taser. The second use knocked him to the ground, and Duncan and a second officer who’d arrived on the scene, David Brewer, began trying to handcuff him, Niess said.

What followed was a protracted struggle in which Knisley became involved, according to Roberts. The struggle attracted the attention of a large crowd of people present in the bar district of the downtown, some of whom were making verbally antagonistic remarks toward the officers, he said. Other officers called to the scene were kept busy maintaining crowd control, he said.

He said the investigations showed that all the officers involved in the arrest, including Knisley, acted appropriately and did nothing wrong.

Included in reports released by Roberts is Knisley’s own report, in which he acknowledges delivering a total of four “hand strikes to the face” of Neal, two at the scene of the arrest and two outside the jail. But he does not acknowledge any such strike inside the jail.

Knisley states in his report that at one point during the arrest, Neal got his left arm free and was swinging it wildly. The open end of a pair of handcuffs that had been snapped on the arm was striking Knisley, knocking off his glasses and ripping his badge from his uniform, he reported.

“I was unable to gain control of the suspect’s arms and I desired greatly that he stopped hitting me on the face with the handcuffs,” he wrote. “I gave the suspect two hard hand strikes to the face in an attempt to gain compliance from the suspect because up to this point in the encounter, nothing else had been effective.”

He further acknowledges that he used pepper spray on Neal after he was handcuffed because he was tensing his body and refusing to cooperate in being placed in a patrol car. He also acknowledges that several “knee strikes” were delivered to Neal, although he does not report if he or some other officer delivered them.