Prisoner hate mail blunder

Milly’s mother, Sally, was sent death threats by Paul Hughes, 36, serving five years at HMP Liverpool for indecent assault.

The prison’s governor has sent a letter to Mrs Dowler apologising for the error, as has the Home Office.

Last week Hughes was jailed for a further five years at Guildford Crown Court in Surrey, where Mrs Dowler lives. He had pleaded guilty to making threats to kill at a hearing in February.

As well as threatening to kill Mrs Dowler, Hughes also claimed that he had murdered her daughter, Milly.

Police found these admissions to be false.

No-one has ever been convicted of the 13-year-old’s murder. She disappeared while walking home from school near the railway station in Walton on Thames, Surrey, in March 2002.

Her body was found in woods in Yateley, Hampshire, six weeks later.

From his cell on Merseyside, Hughes wrote about 20 obscene letters of a sexually explicit and threatening nature to the Dowlers. All were intercepted by prison staff, but one, sent just before Christmas last year, went unnoticed.

Hughes became obsessed with the Milly Dowler case after he was jailed in 2002 for indecent assault.

A Home Office spokesman said yesterday that Liverpool Prison’s governess, Cathy Jones, had sent a letter expressing her "deepest apologies" to the Dowler family.

A letter from the Home Office also offered a "unconditional and profuse apology to the family," he said.

An investigation into how Hughes was able to target the Dowlers from behind bars blamed "a human error by a junior grade staff member".

The spokesman said all letters by prisoners are "scanned" by staff before they are sent.

"Liverpool Prison is the biggest jail in Western Europe, holding around1,600 offenders," he said.

Despite the letter monitoring task at the jail being considerable, he said he was not using this as an excuse. "This was not acceptable," he said.