EDIT: I just realized that this case was in the UK. I don't know how much of what I'm about to say applies to their judicial system, but I'm going to leave it here anyway for those familiar with the UK to comment on.

I did computer forensic work for the US Trustee system. Chain of evidence and the whole deal, because occasionally, our evidence would be handed over to law enforcement and used in criminal cases. I can tell you that at no point during the process should any component treated with any level of disregard. Something called the "chain of evidence" is required in order for anything you find to hold up in court. Here's a brief list of the steps taken when a computer is picked up and examined.

* Arrive at the scene, record the datetime, and fill out your pick-up forms. These forms include information about what is attached to the computer (displays, printers, external hard drives, any random devices, etc). Anything that stores data is taken with. You also catalog the general environment. What was around the computer? Did the place look trashed? Cleaned out? Just moved? Anything meaningful to the case is cataloged on the pick-up form.

* If the systems are turned on, record the datetime and shut them down.

* Unhook peripherals and pack the computers up in the van.

* As you're about to leave, record the datetime and fill out your vehicle mileage log.

* When you get back to the lab, check the computers in to lock-down. More forms including a complete inventory, and (you guessed it) more forms with the data and time on them.

* The computers are stored in a locked room with logged access until they are ready for examination.

* At exam time, you check out a computer or two (recording the datetime!) and head to a lab station. Here, before you do anything, you start to fill out your exam form, which requires that you document every alpha-numeric string you can find on the outside of the computer. We also took photos with a little point and shoot.

* Next it's time to extract the hard drives. You open the system up and pull one hard drive at a time, recording the manufacturer, model, serial number, size, sector count, etc. Anything on the label gets recorded and photographed. You also record where it was attached to (IDE channel and master/slave or SATA port number).

* Once you have the hard drives in hand, you attach them to the write-blocker (we used hardware) and hook them up to the forensic workstation (we used EnCase).

* I'm going to skip the forensic examination portion because it's not relevant to the physical condition of the returned hardware.

* After the examination, we would place the hard disks in protective plastic shells that we purchased and label the drive as evidence with (surprise!) the datetime, case number, and identifying information for the exam form (which linked the drive back to the computer)

* Rinse and repeat for each drive.

* At this point, you have a computer (sans-hard-drives) and a handful of hard disks that you check back in to the lock-up. Hard drives went in a HUGE data-safe fireproof cabinet. The PC case was screwed back on with minimal hardware and put back on a shelf.

* When a case was over, and assuming the debtor in question wasn't brought up on criminal charges and allowed to receive their hardware back, we returned the computers with the hard disks still in the plastic cases, but our labels clearly indicated the computer ID and SATA/IDE channels, so reinstallation was simple. Other times the equipment went to auction. If the equipment went to auction, we'd typically reinstall the drives to get best market value (heh, like that ever happened).

So the point I'm trying to make is this: at no point during the legitimate forensic process should a computer be banged up, subjected to dirt, or generally mistreated. Should this case have gone to court, every single one of those factors could be used by the defense to show mistreatment of evidence. What investigator would want to risk their case on something as simple as maintaining the chain of evidence? This is the #1 thing they hammer in to your head during forensic training.

I don't have any statistics on hand, but cases are won and lost on the basis of sound evidence. Whoever did this did it maliciously and intentionally. There is zero question in my mind.