Illegal transfer of shop ownership outside landlords knowledge

One shop property (cigarette/paan) was rented sometime around 1960's on the ground floor of my residential house. Around 2010 the tenant stopped his business ( due to old age) and went back to his home state. He stopped paying rent and a case was filed for being a defaulter. He got away with it as he started depositing the rent to the rent-controlling office. After few months, another unknown person re-opened the shop and started the same business. However this also stopped after a few months. Now, for the last two years there are more unknown people (mostly local property goons) reopened the shop, and now started changing the shape (reconstruction) and nature (mobile repairing / building material / grocery) of the property as well as business. Suspecting a transfer / selling of the property, we filed an RTI for trade license still bears the first shop keepers name. We got additional information that the property has been sold to these current owner with some kind of agreement. I understand that this is an ideal situation of trespassing and transfer of property without landlords knowledge. I would like to file case for eviction of the tenant. It would be a great help if I get valuable suggestions in this regard.