Minister of State for External Affairs V K Singh said on Wednesday that mental state of the ex-serviceman who committed suicide was not known and the reasons for taking the extreme step should be investigated."He has committed suicide, no one knows what is the reason behind it. Reason for his suicide being reported is OROP, we don't know what his mental state was,(it) needs investigation," Singh said in remarks aired by Times Now news channel.He said One Rank One Pension (OROP),which was pending for past 40 years has been implemented by the Modi government and most demands have been met.Singh said there were "some shortcomings" and a panel was looking into it."You are not ready to wait for it. This is wrong," he said.Asked about Congress Vice-President Rahul Gandhi's visit to Ram Manohar Lohia hospital here, Singh said he is free to go there and take credit for it."There should be no politics over these matters and especially by Congress which sat over the demand of OROP for 40 years," he added.