Falsely claiming that someone committed a serious crime is per se defamation in many jurisdictions. There is no need to prove actual damage. It is damaging by definition.

For libel, you generally have to show harm, but there are some claims that are assumed on their face to be damaging an no proof of harm is needed (libel per-se). Falsely accusing someone of being a serial killer would generally fall into this category.

Edit: I think the harder part would be showing that people would believe the claim (which legally is separate from showing harm). Google could argue that since the box showed the serial killer died in the 80's that a reasonable person would realize it must be a mistake.

I don't think it matters whether they fix it or not. Evidence help with establishing the severity, but in most countries this sort of thing would be classed as defamation of character. This guy should be entitled to something and ought to sue regardless.

Easy to provide when will be detained at random airport for 10 hours until the authorities will triple-check all the info until everybody and the janitor will be satisfied. People has been stopped to take their fly for much less.