It also depends a lot on what media is being used. Magnetic hard drives leave a shadow of the previous writes to the drive behind even after they are overwritten. If you use a different more sensitive read head you can go back as far as 5-10 writes prior. Think of it like peeling back layers of an onion. It takes a lot of time and effort but data can be recovered.
If its memory sticks or solid state drives there are similar processes but I know a lot less about those. Software like bleachbit write random crap over and over to destroy the traces left behind. It also does so in random patterns and numbers of writes. That way instead of knowing for sure the 1st or 2nd the last write is the data you need you have no idea which layer is the data required. That's per sector across thousands of sectors. It becomes a jumbled mess that is next to impossible to reconstruct.
When software like that is set to write junk 10 or even 20 times it doesn't just make a mess it writes over the same spot so many times even the shadow of the shadow is now gone. Its pretty much the only way to use software to truly destroy data. Everything else is physical like degausing the drive with an insanely strong magnetic field or smashing the media part of the drive with a hammer. FYI hard drive platters are carcinogenic so play with them/destroy them with hammers at your own risk.
Deleting a file "permanently"(putting it in the trash then flushing the trash folder) on a magnetic hard drive is the real world equivalent of ripping a piece of paper into eight pieces, wadding it up, and tossing it in the trash can by your desk. There are literally dozens of private companies and crime labs all over the country that can just uncrinkle it and tape it back to 99% the same as it was before.
In some cases there are just tools you can use that will recover the data. Newer hard drives read/write heads are way more sensitive than they used to be a decade ago when I last had to recover a drive. That's assuming the data was overwritten at least once. When most OS "delete" something all they do at first is remove the pointers that say where the data is freeing up those sectors to have new data written on them. There are TONS of recovery tools that a high school computer wiz could manage to use to recover data like that.
Meaning if all they did was power up the machine delete the data and turn it off the data is all still there. A recovery tool will just rebuild the pointers and poof its recovered. If that's what they did then all they really did is add a new charge. Destruction of evidence...
It also depends a lot on what media is being used. Magnetic hard drives leave a shadow of the previous writes to the drive behind even after they are overwritten. If you use a different more sensitive read head you can go back as far as 5-10 writes prior. Think of it like peeling back layers of an onion. It takes a lot of time and effort but data can be recovered.
If its memory sticks or solid state drives there are similar processes but I know a lot less about those. Software like bleachbit write random crap over and over to destroy the traces left behind. It also does so in random patterns and numbers of writes. That way instead of knowing for sure the 1st or 2nd the last write is the data you need you have no idea which layer is the data required. That's per sector across thousands of sectors. It becomes a jumbled mess that is next to impossible to reconstruct.
When software like that is set to write junk 10 or even 20 times it doesn't just make a mess it writes over the same spot so many times even the shadow of the shadow is now gone. Its pretty much the only way to use software to truly destroy data. Everything else is physical like degausing the drive with an insanely strong magnetic field or smashing the media part of the drive with a hammer. FYI hard drive platters are carcinogenic so play with them/destroy them with hammers at your own risk.
Deleting a file "permanently"(putting it in the trash then flushing the trash folder) on a magnetic hard drive is the real world equivalent of ripping a piece of paper into eight pieces, wadding it up, and tossing it in the trash can by your desk. There are literally dozens of private companies and crime labs all over the country that can just uncrinkle it and tape it back to 99% the same as it was before.
In some cases there are just tools you can use that will recover the data. Newer hard drives read/write heads are way more sensitive than they used to be a decade ago when I last had to recover a drive. That's assuming the data was overwritten at least once. When most OS "delete" something all they do at first is remove the pointers that say where the data is freeing up those sectors to have new data written on them. There are TONS of recovery tools that a high school computer wiz could manage to use to recover data like that.
Meaning if all they did was power up the machine delete the data and turn it off the data is all still there. A recovery tool will just rebuild the pointers and poof its recovered. If that's what they did then all they really did is add a new charge. Destruction of evidence...
and Q was right... these people are stupid.