Among the conditions for cutting off the hand of a robber are the following:
1. Puberty,
2. Sanity
3. Freedom or free will
4. Not being compelled,
5. The thief should break into a protected area alone or with someone else,
6. Take out the object from the protected place,
7. The robber should not be the owner's father.
8. The breaking into and robbery should take place secretly. Hence, if he takes out and away an object openly, his hand is not severed. In fact, if he breaks into a locked building secretly but then he takes away the object openly and while he is being seen, his hand is not cut off.[1] The Arabic word "herz" has been defined as a locked (protected) place.[2]
9. The limit for the stolen commodity. If a thief's hand has to be cut off, the property which he steals must reach one fourth of pure gold coin or else its value should reach a quarter of such dinar.[3]
Keeping the above points including the fifth condition into consideration, we come to the conclusion that the robber or thief must in all stage be considered as being involved intentionally and deliberately.[4] If the protected place is broken by someone other than the thief or his accomplice and the thief takes away the object, it will not cause his hand to be cut off because it is as though he has stolen from an unprotected place.
In your supposition, a similar condition is assumed because the thief has stolen from an unprotected place and the protected place had been broken by someone else before him or by him but unintentionally.
The viewpoint of Ayatollah Mahdi Hadavi Tehrani in this regard is as such:
One of the conditions for a robbery or theft which causes the hand of a robber to be cut is stealing from a locked place. However, in the above case the condition is not met and the punishment is not enforced upon the thief.
May Allah grant you success.

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