If I were going to approach a vehicle whose driver was suspected of homicide, I would do so in a very obvious, slow, and non-threatening manner, probably without obviously being a cop. The last thing I would want to do if someone is potentially a hair trigger threat is give them a surprise and cause them to start shooting.
Police could solve a ton of these issues if they investigated before they tried to apprehend. If we're going to live in a surveillance state, use the damn surveillance for situational awareness. Right now, the cops just get a hit like "APB - Homicide" with no retrospective analysis or attempt to verify. It's essentially an unverified tip - they should use some expertise and tools to try to validate it before they commit.
But they don't, because there's no cost or penalty to them for overreacting, and there's a risk if they underreact. It's really an incentives problem. I don't know if the right spot to address it is with the individual officers or the department, but someone should have some huge liability for this mistake.