Unsolved Leeds murders: The deadly arson attack that killed elderly couple Margaret and Patrick Spencer

Patrick and Margaret Spencer were trapped upstairs in their home in Sandiford Terrace, Manston, as a neighbour raised the alarm in the early hours of July 21, 1999. Firefighters broke into the semi-detached house to rescue the pair but the time spent amid the smoke would ultimately prove fatal. Mrs Spencer, 77, died at St James's Hospital later that day and 85-year-old Mr Spencer - known as Pip - died in hospital 50 days later, having never been well enough to return home.

In the latest in our series on unsolved murders in Leeds, we look back at the exhaustive police investigation which saw hundreds of interviews conducted and multiple arrests made as detectives tried to make sense of a fire started at the home of a well-liked elderly couple.

Grandparents Mr and Mrs Spencer, who celebrated their golden wedding four years earlier, had lived in Sandiford Terrace for most of their lives. Mr Spencer had served in the Army for 37 years before becoming a security officer at Vickers in Barnbow until his retirement. He met his wife-to-be when she was in the army's Auxiliary Territorial Service.

The couple played bingo regularly at the nearby Cross Gates and District Recreation Hall Club and were said to have been keen gardeners and avid crossword fans. The idea that anyone would want to harm them was beyond belief for those who knew them, with neighbours saying they were "horrified" and one of Mrs Spencer's bingo partners describing it as a "senseless" thing to do.

As fire service and crime scene investigators examined the house in the wake of the fire, it quickly became clear that it was no accident. During a press conference the following day, lead investigator Detective Superintendent Eddie Hemsley appealed to anyone in the Manston or Cross Gates area who had experienced a minor fire - which they may not have reported - to get in touch. He said that, in his experience, arsonists first experimented by starting minor fires, adding: "These minor fires escalate into something more serious - possibly like something we are investigating."

He said Mrs Spencer, who died of heart failure with smoke inhalation as a secondary cause, had managed to speak to officers but could not think of any reason why anyone would want to attack their home. One theory among many explored during the investigation was that the house had been targeted in error. The initial appeal by police brought forward information on six mystery fires near the couple's home, leading Det Supt Hemsley to say he was leaning "more to the conclusion that the fire at the Spencer's home was a random attack rather than them being singled out".

The unexplained, small fires in the immediate vicinity of the house had all happened in the six weeks prior to the arson attack on the couple's home. Four had involved estate agents 'for sale' signs being set alight. A fifth involved material being set alight on a window ledge of a house and the sixth was a small fire in the porch of St James's Church, Church Lane.

Detectives also sought evidence of any confrontation or conflict in the days prior to the fire. In August 1999, they asked the public to identify two teenage boys seen outside the couple's house about four weeks before the fire - in mid to late June. Mr Spencer had spoken to the boys at around 8.30pm or 9pm as he asked them to move on, which they did without argument. The boys were described as white, 16 to 17 years old, of medium build and wearing tracksuit bottoms. They walked off up Sandiford Terrace and into Sandbed Lane.

The investigation team wanted to identify the occupants of a car that entered Sandiford Terrace about 1.30am on the date of the fire as well. A neighbour heard a car door slam and a car engine running, but also heard muffled speech and possibly someone was being dropped off.

Sharing his thoughts at the time, Det Supt Hemsley said: "Someone may have had a grudge against the couple. Patrick was of the old school, an Army man, and even at 85 he was not afraid to come out and ask local youths to move on. But they were very minor arguments, to do with parking in the street and rubbish. Not the sort of thing that would make you come back and set fire to someone's house. I keep asking myself why that house, why that couple?"

Meanwhile, forensic teams were building a more detailed picture of how the fire itself had started. They established that inflammable liquid had been poured through the couple's letterbox and ignited using a wick made out of cotton-like material. The metal letterbox flap was missing and detectives believed the arsonist took it away.

Also in August 1999, the arrival of an anonymous letter marked "urgent" at Killingbeck Police Station brought hope of a potential breakthrough. It would occupy the investigation team for months as appeals were made for the author to come forward and a handwriting expert was drafted in. House-to-house enquiries were conducted and a database was used to identify possible candidates who were asked to write down a sequence of words, including phrases used in the letter itself.

The letter was later found to be a hoax, with a resident of Sandiford Terrace being charged with perverting the course of justice in January 2000. Brenda Wilby, who lived opposite the couple and had a history of mental illness, took her life before the case came to trial. In a note found by her husband, she maintained that she had nothing to do with the arson attack.

While her letter to police had been a key area of focus, it was by no means the only avenue being pursued. The independent charity Crimestoppers had put up a £5,000 reward following Mr Spencer's death in September 1999 and the Yorkshire Evening Post had pledged to match the sum. Det Supt Hemsley said: "I hope the reward will prompt someone to ring us if they have any suspicions about anyone. We are concentrating our inquiries in the Manston and Cross Gates area and believe the killer lives locally or frequently visits the area. I would ask people to look closely at their neighbours and acquaintances and ask themselves if there is anything different about them since the fire that makes them suspect they could be responsible".

In December that year, it was revealed that a hooded man had been seen five nights before the arson attack as he lurked in a snicket that led to the couple's garden. The man had been spotted at 3.10am on July 16 and walked off towards St James's Church graveyard when he realised someone had seen him. The man was described as being aged 20 to 23 and 5ft 10in, wearing a black cagoule-style jacket with the hood pulled up and dark trousers or jeans.

It emerged that a number of back garden sheds in Sandbed Court were raided overnight on July 14 into July 15 - 24 hours before the hooded man was seen. The gardens were accessed via the snicket that ran to Sandiford Terrace. The garage belonging to the Spencers' next door neighbours was also burgled, with a mountain bike and power tools being stolen.

Det Supt Hemsley, said: "A link between this hooded man, burglaries in the area and the arson attacks cannot be discounted. The arsonist may be a burglar with an inclination to start fires - the accelerant used to commit the offence may have been stolen from a shed or garage. We need information about this man."

On the first anniversary of the fire, the burglaries and the potential link to the arson attack were still being explored and the hooded man remained unidentified. The couple's daughters, Christine Stansfield and Valerie Spencer, also spoke about the devastating loss of their parents.

Mrs Stansfield said: "It's literally shattered our lives. It's something that is constantly with us. An hour doesn't go by without thinking about them. We feel very cheated. We are getting used to the fact they are not there, but that doesn't make it any easier. I don't think we will ever accept the way that they died."

In November 2001, an inquest into the couple's deaths concluded that they had been unlawfully killed in what Coroner David Hinchliff described as a "motiveless and futile" attack. The court heard the police investigation had involved more than 1,000 interviews and six arrests being made. Det Supt Hemsley said he hoped a DNA profile might eventually lead to a breakthrough, adding: "They were a respectable couple and this was totally unjustified. Although two years have now passed, we have not given up hope that we will bring the offender to justice for this very callous attack."

Anyone with information that could help investigators to solve the case can contact West Yorkshire Police on 101 or Crimestoppers on 0800 555 111.