A father accused of bashing his young son to death with a brick was found dead in a Sussex prison after apparently electrocuting himself.

The body of Dafydd Field, 52, was found in his cell at Lewes prison just before 7am today.

He was not on suicide watch at the time.

Now prison bosses and Sussex Police have launched a joint investigation into what happened inside the cell.

The teaching assistant had phoned police at 10.30am on April 4 to say he had killed his son Jethro, six, at the family home in Farncombe, near Godalming, Surrey.

Officers went to the house and found the boy's battered body in an upstairs bedroom, Surrey Police said.

A post-mortem examination carried out the next day found Jethro died from head injuries caused by a brick and from having his throat slashed with a knife.

He had also been stabbed in the chest.

Field, who was born in England but had family connections in Wales, handed himself in to police in Tywyn, Gwynedd, South Wales, two hours after Jethro's body was discovered.

He was brought back to Surrey, where he was interviewed at Guildford police station on Friday before being charged with his son's murder.

The following day Dorking magistrates remanded him in custody to HMP Lewes in East Sussex, and he had been due to appear at the Old Bailey on July 7.

A Prison Service spokesman said: "Next of kin have been informed. Every death in custody is a tragedy and, as with all deaths in custody, the Prisons and Probation Ombudsman will conduct an investigation."

Field had been married to his wife Stevie for 10 years but the couple had been living apart for almost a week at the time of Jethro's death, Surrey Police said.

The couple were not divorced and had an "amicable arrangement" whereby they both looked after their young son.

In his phone call to police after the killing, Field asked officers to go to his house before his wife arrived to collect Jethro for the day.

Detective Chief Inspector Maria Woodall, the senior investigating officer in the case, said it had been a "tragic episode" for Jethro's family and they were still trying to come to terms with all that had happened.

She said: "We will continue to gather evidence for a coroner's inquest into Jethro's death, which will take place at a date to be set in the future."

The inquest into Jethro's death was opened in Woking, Surrey, today.

Surrey coroner Michael Burgess heard that the boy's lifeless body was found on a bed in one of the rooms of his family home.

A forensic pathologist concluded he had died from injuries to his neck and head and further inquiries into the cause of death are still to be made, the inquest was told.

Jethro's mother, Stevie Field, paid tribute to her young son's "happiness, inquisitiveness, sense of humour, strength and love".

She said in a statement: "I would like to send thanks from myself, and Jethro's brother and sisters, to all our friends, family, neighbours, colleagues, the police and the entire community for their amazing compassion, love and support at this dreadful time.

"Your support has helped us to start coming through this ordeal.

"We will forever miss Jethro. He was such a special boy and no words can express how sad we feel.

"We will all miss his happiness, inquisitiveness, sense of humour, strength and love. Be at peace, darling."

Police said Jethro had a sister, aged 16, and a 19-year-old brother from his mother's previous marriage, and another sister, aged 16, from his father's previous marriage.

He was due to turn seven on April 27.

Neighbours in Farncombe, a small commuter town, were stunned at the latest developments.

Cicely Hill, who lives opposite the family, said Field had seemed "a devoted father" and was devastated to hear of his death.

She said: "I suppose he thought he would have to live with it for the rest of his life.

"I could not understand him doing it in the first place. I didn't know him that well but I'd seen him with the children and he was great with them."