[comrade1]

I'm curious, have companies like this ever been subpoenaed for their data as part of a fishing expedition to catch a criminal or find the father of a child for child support, etc?

To example, there's been a few examples where they found someone through relative('s) DNA for murders in the past, but DNA was voluntarily given.

[vijayr]

If one gives their DNA voluntarily (for a particular case) and they are cleared of any wrong doing, is their DNA information still kept on file by law enforcement?

[DanBC]

England has an extensive DNA database (largest in the world) and it's hard to get taken off it, even if you voluntarily give your DNA. http://news.bbc.co.uk/2/hi/uk_news/7532856.stm

> Innocent people who volunteer to give a DNA sample during a police inquiry, for instance to help narrow a police search in a major murder investigation, also have their details kept on record.

Most people don't volunteer their DNA; it's taken off them when they're arrested, and it's kept even if they're not convicted. It's even kept if they're released without charge, although there are time limits for that after a 2008 case. http://news.bbc.co.uk/2/hi/uk/7764069.stm

[gwern]

Voluntarily or not, the answer is usually yes: http://www.nytimes.com/2009/04/19/us/19DNA.html https://en.wikipedia.org/wiki/National_DNA_database