A needle assembly is able to collect a sample of biological material in a needle of the assembly. The needle assembly has a safety shield capable of being moved on the needle assembly to cover a sharp tip of the needle assembly. The shield can be locked in place over the sharp tip by a locking mechanism. The assembly further includes an obturator that can be inserted into the needle to remove the sample from the needle. A reset member associated with the obturator is capable of engaging the locking mechanism to release the locking mechanism and allow the shield to be moved away from the sharp tip.