Look at Kyle Fisher's right eye. Behind his drooping eye was a damaged brain. Look at his head. It was abnormally big. Babysitter Suzanne Holdsworth - free today after a retrial - spent three years in prison after she was convicted in 2005 of murdering Kyle because of this simple logic: Kyle was essentially healthy, then he was killed. The simple logic was wrong - Kyle's brain had five separate disorders - and that mistake led to a terrible miscarriage of justice. That miscarriage only became clear when Newsnight reported on it a year ago when Ms Holdsworth was still in prison, and was only righted when a jury at Teesside Crown Court found her not guilty. After Ms Holdsworth, 38, was convicted in 2005, Cleveland Police boasted of "a relentless investigation" led by Det Supt Tony Hutchinson, the now retired "super cop" who nailed "canoe man" John Darwin. Far from being relentless, too many things that should have been investigated properly were not investigated. Ms Holdsworth was alleged to have smashed Kyle's head against the banister at her home. But there was no visible blood, no hair, no skin on the banister, and no DNA test was carried out. The accused's partner, Lee Spencer, who has stuck by her throughout, told me: "They didn't do a DNA test on the alleged murder weapon. "I'm no Sherlock Holmes, I drive a cement mixer, but what kind of investigation was that?" Earlier injury The babysitter said in her frantic 999 call that Kyle was suffering from a fit - and never changed her story. Home Office pathologist James Sunter, now dead, reported after the toddler's death in July 2004 that Kyle's brain was essentially normal - one of eight findings he got wrong.