Swamy took to Twitter on Thursday and posted a document to support his claim.
"Why I think Sushanth Singh Rajput was murdered," Swamy tweeted along with a photograph of the document that has 26 points.
According to the document, the mark on Sushant's neck did not indicate suicide but instead hinted at homicide.
The document further claims that for suicide by hanging, one has to hang himself by removing the table under his feet. "This huge force is not possible in homicidal strangulation," read the document.
The document further reads that marks on his body indicate "beating".
This comes a day after Swamy spoke to Bihar Chief Minister Nitish Kumar and said that he will initiate a CBI inquiry into the matter.
Sushant was found dead at his residence in Bandra, Mumbai on June 14. Post mortem report stated the actor had committed suicide. The police are still investigating the case.