Adam Parkin, 35, killed his wife Julie, stabbing her more than 20 times in a savagely brutal assault at their home in Kirkwall Close, Sunderland, last June. Schoolteacher Julie, who worked at West Boldon Primary, had stumbled upon evidence of her husband of nine years' deviant sexual preferences and challenged him about them. Following the murder, Parkin drove to a police station to hand himself in was jailed for a minimum of 23 years at Newcastle Crown Court last October.The case returned to court today after a reference by attorney general, Jeremy Wright QC, on the basis that the term was too soft. But although top judges said Parkin's crime had ruined lives, they refused to increase the term he will serve. Appeal judge, Sir Brian Leveson, said the 23 years Parkin must serve before even applying for release was "not unduly lenient". The court heard 39-year-old Julie had discovered evidence of his involvement with pornographic images of a child. They went out for a drive to talk, but when they returned to their home, he took a kitchen knife and killed her in a savage attack. One of the blows was so forceful that it left the blade of the knife embedded in Mrs Parkin's skull. At Southwick Police Station, the blood-covered Parkin begged for help, saying he had killed his wife. He later made a statement, in which he said he should have killed himself instead, adding: "She was so sad when she found out what I really am". Investigation of his computer revealed a search history suggesting an interest in child sex, including a search for "Cambodian child abuse". Sir Brian, sitting today with Sir Roderick Evans and Mr Justice Jeremy Baker, said Parkin had caused intolerable loss to his wife's family."It is not difficult to understand the enormous impact this offending has had upon all those other affected by it," he said. "All spoke of the loss that they have suffered and the loss of a close and caring relationship which was likely to have an enduring and devastating impact. "The damage caused will ripple out forever." For the Attorney General, Duncan Penny QC argued that a 23-year term was not long enough to mark the seriousness of the crime. But Sir Brian refused to increase it, saying: "In our judgment, this sentence was not unduly lenient". Parkin appeared for today's Court of Appeal hearing via a video link from Durham Prison. He had pleaded guilty to murder, the attempted murder of another person who cannot be identified and three child porn offences