Something else is happening here
I can't for one second, think that anyone would take servers home with them or cut cables unless those items were owned by the support company. Other than theft, it will come under the computer misuse act. No IT person regardless of how bitter they are would go this far upon dismissal.
I suspect the kit was supplied and there is a disputed bill. If the invoice states ownership remains with the IT company until the bill is paid, then (s)he would remove the equipment. Perhaps the IT person was on a contract, and at the end of the minimum period wasn't fully paid up to date, so took the personally owned / unpaid equipment to recover losses.