A man charged with murdering a baby said he fell over a dog and landed on the child.

Mark Lamb told police officers he had fallen over on top of baby Joseph, kneeing him in the chest, Lewes Crown Court heard. The baby died of a ruptured heart and also had broken ribs.

Lamb, formerly of Rye Street, Eastbourne, denies murder. He also denies three charges of cruelty and wilful neglect to Joseph, whom he treated as his own son. The baby's mother, Jennifer Harrington, 21, also denies three charges of cruelty and wilful neglect.

Prosecuting, Brian Barker QC said a post mortem found that there were at least three other sets of fractures to Joseph's ribs, some dating back weeks. The injuries to Joseph were not accidental, he said yesterday.

The unemployed couple lived together with Joseph, another 18-month-old son, and a dog in a one bedroom council flat. The court heard friends and relatives were constantly coming round and space was cramped.

After Joseph was born in July 1998 he was carefully monitored because Harrington's first child had died of cot death. She was described in court as "not having a huge maternal instinct" and the burden of care fell on Lamb.

On the night of September 2, 1998, neighbours heard arguing and crying, the court heard. The following morning Joseph was dead. A friend who was staying in the flat called an ambulance.

When Lamb and Joseph arrived at Eastbourne District General Hospital he was cradling the baby saying "I'll kill myself. It's my fault, I fell on the baby", the jury was told. He said he had been having a cigarette at the kitchen door while Joseph was lying on the floor.

Lamb said he tripped over the dog and fell on the child's chest with his right knee, the court heard. The case continues.

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