Here in Denmark criminal records becomes inaccessible to non-government actors 2-5 years after sentence served, depending on the severity of the crime, and 10 years for the government/public sector. In theory it's never wiped and keeps being accessible to the Danish Security and Intelligence Service, so it may still affect your ability to get a security clearance.

There is the caveat though that names are allowed to be published in some cases of more severe crime, so in cases like murder an employer might still be able to find out about it with a google search.