he was old man with curly hair slim built and average tall-the shadow shown in the Cassette exactly looking like him -it resembles billu also but curly hair makes confusion which is matching to mamaji's photo.
he has got all the motive to kill ksa because of his sisters death.
I have got feeling that he was dakait and his sister was killed by ksa accidentally -
in deep down my heart I think billu is also involve some what in this case because he was the one who bring arjun's childhood file from orphanage it is possible it is his and rudra's set up on Arjun.
and may be rudra and arjun's mama has set up this plan and Arjun is real alluwalia and arohi is adopted daughter.may be arrohi is illigmet child of that lady and Rps, mmamaji has exchange the child left arjun in jungle and now taking revenge on allu's by framing their own son so in any case allu's are looser.
that is the reason why Amrit said she don't know who will win but allu's will defiantly loose the case it clearly indicates on both the side allus are going to loose-it indicates past raj and amrit knows arjun is alluwalia and may be he is son of sudhir.