Update only data and remain at the same task

I have a situation where at approver level in a process, I just want the approver to UPDATE the status of task in a business variable and hold the task till he verifies all data. The complete data verification takes a day or so.

What I mean is, a case comes to approver with some attached documents. The approver shall just update a status business variable to say "In Process" and verify the documents and data submitted offline out of the system. The case shall remain with him. It shall not move to next stage. When he is done with all the offline verification, he shall press some sort of SUBMIT button and update the status business variable to "Verified" and now the task shall move to next level of approver.

How can I implement such a STATUS UPDATE ONLY task in Bonita?