The wrinkle in this case is that the thumb print giver was in parole. The conditions of parole stated that failure to divulge phone pass codes on phones could result in arrest and phone seizure “pending further investigation”. The parole conditions didn’t say anything about forcible thumb print taking.

So the logic here seems to be:

• If he had agreed to unlock the phone then the result would be the same.
• If he refused to unlock the phone, that is a legitimate grounds for arrest. Fingerprinting is a routine part of being arrested, so there’s really no harm if it’s done on a phone in a patrol car. Either way, the result would end up about the same.

Especially talk to FSF if this “well known debugging tool” is a part of the GNU project, as FSF has the power and standing to enforce the copyrights on GNU software.

Ctrl+alt+delete was a separate interrupt line direct from the keyboard. That is, when you pressed the three keys, the interrupt signal was asserted, causing the CPU to jump to the interrupt service routine, which should be in the source code package.