A five-month old baby boy may have died after contracting a lethal bacterial infection from terrapins owned by a family friend - which had been handled by his father shortly before his death, an inquest heard.
Tyler Wilson was found dead and tests later revealed he had died from an acute Salmonella infection which is particularly harmful to the very young and elderly.
His parents Lindsey Wilson, 37, and Tim Lees, 34 were initially investigated on suspicion of neglect following the salmonella finding, the hearing was told.
But senior coroner Professor Paul Marks ruled at the hearing in Hull, East Yorkshire, that the child had died from natural causes on November 25, 2014, and the inquest was told they had been completely cleared of any blame.
In a statement read to the inquest, paediatric infectious diseases expert Professor Nigel Klein said that terrapins - which had been handled by Tyler's dad Tim Lees - could have been the source of the salmonella but it was impossible to identify.
Infants are particularly at risk of contracting salmonella and terrapin turtles commonly carry salmonella bacteria on their outer skin and shell surfaces.
Tyler suffered no symptoms but on the morning of his death he was discovered unresponsive by mum Lindsey as she was changing his nappy.
The panic-stricken parents, who have five other children, ran out of their home in west Hull screaming for help.
Neighbours rushed to their aid and performed CPR in the street before ambulance crews arrived.
Speaking after the inquest, dad Tim said: "Tyler was always happy and always smiling. He was such a lovely baby and our little monkey. He was loved by everyone."
Tyler's mother added: "He was a chunky monkey and a really good baby. All his brothers and sisters loved him.
"He was a bonny little thing and would bounce with excitement when his brothers and sisters were around.
"He was like my best friend and I would talk to him all the time.
"He came at a time when his sister was fighting for her life with aplastic anaemia.
"He helped both of us get through such a difficult time. But Tyler died just as my daughter was getting better."
In a statement, Lindsey told the inquest about the desperate attempts to save her baby son.
She said: "Other than a chest infection Tyler had never been unwell before.
"On the day he died I fed him a bottle and then we got the other children ready for school.
"I came back to change his nappy which was soiled. I started putting his trousers on when I realised he wasn't moving. I poked him but I got no response.
"I called for his dad and he picked him up. I them ran into the street screaming for help. Neighbours came and tried to resuscitate him.
"The ambulance crews arrived and we went to hospital. I watched the doctors and nurses work on him but they couldn't save him."
In statements read out in court, neighbours described rushing to help and their attempts to carry out CPR in the street.
One said: "When I went over the baby was blue in colour. I was in shock. My adrenaline was pumping and I quickly called 999 as the baby remained unresponsive.
"It was a distressing situation. We just tried to do as much as we could to help.
"The whole thing really traumatised me. I am a father myself and I just wanted to forget it had happened but I still get flashbacks."
Paediatric histopathologist Dr Luiz Peres confirmed Tyler died of acute salmonella infection.
Feeding bottles were tested for the infection which proved negative.
Dr Peres admitted he could not say how Tyler had contracted it but that it usually it comes from food or contaminated water.
It can also be passed from people to people.
The inquest also heard from a report by paediatric infectious diseases expert Professor Nigel Klein who confirmed the feeding bottles were seized but found to be clear of contamination.
Senior coroner Professor Paul Marks concluded Tyler died of natural causes and made it clear the parents were not to blame.
He told the parents: "I would like to extend my condolences to you at the sad loss of your son who had completed your family. This has been a heartrending story.
"You did your best to resuscitate him and you should not blame yourselves at all."
Detective Constable Elizabeth Thompson told the inquest Tyler's parents were completely cleared of any blame.
After the inquest Tim said the investigation had delayed Tyler's burial.
He said: "It was seven months before we could bury Tyler who we laid to rest the day after his first birthday.
"It has been an incredibly difficult time particularly when people point fingers. It is a relief that this is finally over."