His searches included phrases like "son kills mother for miscegenation", a word meaning the mixing of different racial groups through marriage, cohabiting, sexual relations and procreation.
Speaking after Mair's whole life sentence was handed down, Mr Cox said: "To the world, Jo was a member of Parliament, a campaigner, an activist and many other things.
"But first and foremost she was a sister, a daughter, an auntie, a wife, and above all a mum to two young children who love her with all their being.
"We try now not to focus on how unlucky we were to have her taken from us, but how lucky we were to have her in our lives for so long.
"To the person who did this we have nothing but pity - that his life was so devoid of love and consumed with hatred that this became his desperate and cowardly attempt to find meaning," he added.
"The killing of Jo was a political act, an act of terrorism, but in the history of such acts, it was perhaps the most incompetent and self-defeating.
"An act driven by hatred which instead has created an outpouring of love. An act designed to drive communities apart which has instead pulled them together. An act designed to silence a voice which instead has allowed millions of others to hear it.
"As a family, we will not respond to hatred with hatred. We will love like Jo did and know that, although she is dead, the ideas and values that she held so dear will live on.
"We hope the country will also take something from this - that Jo's death will have meaning.
"That those in politics, the media and our own communities who seek to divide us will face an unassailable wall of British tolerance and the articulation of Jo's belief that we hold more in common than that which divides us."