What witness said anything about a smirk?
Jack Tatum.
How old are you? Do they allow that you use the kindergarten computer?
Jack Tatum said Oswald's "mouth curled up...kind of a smile". Tatum didn't use the word "smirk", but instead stated that Oswald's mouth curled up; a smirk (in my opinion) though Tatum didn't use that actual word.
Naughty, naughty, Bill. You shouldn't put your opinion (smirk) into somebody else's statement. Other less discerning posters might believe you.
“He (Oswald) wasn’t panicking, that was for sure,” Tatum said. “The one characteristic about Oswald that I saw and will never forget was that his mouth seemed to curl up as if he was smiling. And I saw that when he was looking into the squad car before the shots. I noticed that same characteristic when I saw him (Oswald, later) on TV.
“He was already down and I saw a person (positively identified by Tatum as Oswald) with a gun in his hand and he turned around, as if he was going to run off or walk off and as he got to the rear of the car, he hesitated and walked around the squad car (towards the officer) and shot a fourth time. It could have been a third.” [21]Tatum stated that six to ten seconds elapsed between the penultimate shot and the last shot.