Divorce does not occur by obtaining a thumbprint on a blank paper

What do the scholars of religion say regarding this matter:

Zaid forcibly obtained a thumbprint from Bakr on a blank piece of paper, and subsequently, it became rumored that Bakr had divorced his wife. The question is: does divorce take place merely by obtaining a thumbprint, without having the words of divorce uttered verbally, and with the intention that the content of a divorce deed would be written upon it later? Please clarify, and you shall be rewarded.

Roshan Ali, resident of Narayanpur, District Basti.