The senseless murder of BBC librarian Tom Brown remains unsolved a year after his death.

Despite a massive police manhunt, a television appeal on BBC's Crimewatch, and a £20,000 reward, Mr Brown's killer has never been caught.

Now on the anniversary of his death, police have renewed their appeals for information to the brutal stabbing that shocked Southgate.

Leading the investigation, DCI Garnish said: "We continue to appeal for anyone who may have seen or heard anything suspicious to contact us.

"Southgate High Street is a busy road and we are certain that someone must have seen something on the evening Tom was attacked."

Mr Brown, 27, of The Green, was walking home from a friend's flat in Mayfair Terrace, Southgate, at around 3am on August 21, 2004.

He walked along Chase Road, across Southgate Circus and headed south into the High Street. When he reached The Green outside Chandos Court he was attacked and stabbed.

Police ruled out robbery as a motive after his mobile phone and wallet were found on him by an ambulance crew who arrived at the scene.

But DCI Garnish is keen to talk to several witnesses who were spotted in the area at the time of the murder and may hold vital information.

He is keen to trace a scruffy white man seen at the time Mr Brown was attacked. He was slim, around 5ft 7ins tall, with a gaunt-looking face. He had light brown hair, short at the sides and longer at the front.

Officers are also keen to talk to a man and a woman who were seen sitting on a wall at 4.10am, just ten yards from the murder scene.

Witnesses also described seeing a man with a female friend close to the murder scene at about 2.45am. The man was in his late 20s, of medium build, with short dark brown hair, a round face and full lips. He was wearing a beige or grey coloured tracksuit top with a hood and matching bottoms.

The woman was in her late 20s, slim and around 5ft 4ins tall. She had shoulder length curly, black hair and a noticeable tan. She was wearing a black three-quarter length leather coat.

Another couple were seen walking along The Bourne in Southgate, heading towards Palmers Green, and arguing about a forthcoming holiday.

DCI Garnish said: "A year after Tom's murder, we continue to appeal for anyone who may have been in the Chandos Court area between 3am and 4.15am that morning.

"Although it is possible that our witnesses have seen the same couple at different times in the evening we are at this early stage treating these sightings as two separate couples.

"They may have significant information which could assist us and we urge them both to come forward as soon as possible."

Police also released footage on Crimewatch last Septemeber of two men running along Meadway in Southgate at 3.48am, but they have not been identified.

Anyone with information should contact the incident room on 8345 3714, or Crimestoppers anonymously on 0800 555111.