Even though I believe Brazilians speak Portugese as their primary language, you'd expect him to understand "STOP" in English.
1) how many people were around him?
2) did he know they were referring to him?
3) didn't I read undercover guys were telling everyone to scatter
4) did they yell stop or halt?
5) this was a tragic mistake but lets not assume this guy knew he was running from police. He may have thought they were telling him to scatter along with other bystanders.
6) at the very least, this is not a black and white issue.