Title: Hammersmith nude murders
Content:  For Du Rose, the most likely suspect was a Scottish security guard called Mungo Ireland, whom Du Rose first identified in a BBC television interview in 1970 as a respectable married man in his forties whom he codenamed "Big John". Ireland had apparently been identified as a suspect shortly after Bridget O'Hara's murder, when flecks of industrial paint were traced to the Heron Trading Estate, where he had worked as a security guard. Shortly after this connection was made, Ireland committed suicide by carbon monoxide poisoning, leaving a note for his wife that read: "I can't stick it any longer", and finished, "To save you and the police looking for me I'll be in the 
Title: Murder of Peter Falconio
Content:  Land Cruiser 4WD identified, and on the thirty-six men whom callers had identified in the footage. Based on these results, police interviewed Bradley John Murdoch in Broome on 1 November 2001, though Lees' descriptions did not immediately connect the case to him and no DNA sample was collected. On 17 May 2002, investigators caught Murdoch's drug-running accomplice, who began to relate details of his connections to the case, and a DNA examination of Murdoch's brother also supported his involvement. Murdoch then disappeared, but on 22 August 2002 he was arrested and tried on an unrelated kidnap and assault charge by South Australia Police.
Title: William Martin (Royal Marine officer)
Content:  Montagu stated that the body was released on the condition that the man's real identity would never be revealed. However, in 1996, Roger Morgan, an amateur historian from London, uncovered evidence in the Public Record Office that the identity of the corpse was a Welshman named Glyndwr Michael. Michael was born in Aberbargoed in Monmouthshire in south Wales. Before leaving the town, he held part-time jobs as a gardener and labourer. His father Thomas, a coal miner, killed himself when Michael was 15, and his mother died when he was 31. Homeless, friendless, depressed, and with no money, Michael drifted to London where he lived on the streets. He was found in an abandoned warehouse close to King's Cross, seriously ill from ingesting rat poison 
Title: Murder of Peter Falconio
Content:  man captured in the CCTV footage at the service station at 12:38 am. This indication was later corroborated by Murdoch's own father as well as his business associate, James Helpi. The police found traces of Murdoch’s DNA on a pair of homemade handcuffs used in the attack. This, combined with the DNA match on Lees' T-shirt, allowed Murdoch to be charged with the murder. The T-shirt DNA was found to be "150 quadrillion times more likely [to] belong to Murdoch" than anyone else. His DNA was also found on the gearstick of the Kombi in which Falconio and Lees had been travelling, and which, subsequent to the attack on the Stuart Highway, was driven by the 
Title: Clocaenog Forest Man
Content:  In June 2016, the police released a photograph of the victim's jawbone in the hope that dentists may recognise their dental work and therefore identify the victim. The police also announced that they were undertaking familial DNA research. On 26 September 2016, police released images showing how the man could have looked when he was alive at the ages of 50, 60 and 70 on the BBC Crimewatch programme. In March 2017, the police confirmed that they had been contacted by, and met with, serial killer Peter Moore following his claims that he knew the identity of Clocaenog Forest Man. Moore claimed in a letter that the victim was a mature student at Aberystwyth University who had disappeared in 1996. Moore did not disclose the victim's name but Daily Post journalists identified a Roger Evans of Bradeley near Stoke-on-Trent who disappeared on 16 January 1996, aged 46, during his first year at Aberystwyth University. It was later reported that his theory had been discounted by the police due to conflicting dates. In October 2017, police support officers and race marshals distributed leaflets to attendees of the 2017 Wales Rally GB.
Title: Franz Müller
Content:  When the train reached Hackney Wick, the guard was alerted by two bankers who discovered pools of blood in Briggs' compartment. Police later found a black beaver hat. Initially it was presumed to have belonged to the deceased but it subsequently turned out to have belonged to the murderer. On 18 July, a cab driver called Matthews came forward with suspicions about a German man known as Franz Müller. He told police that the 24-year-old tailor had come to his house with a gold chain in a box. After he had attached his fob watch to the chain, Matthews gave the box to his daughter. The box had been sold by a jeweller in Cheapside, who identified Müller from a photograph and told investigators that the German had visited his shop on 11 July to exchange a gold chain. This was later identified as belonging to Briggs. With this evidence, a warrant for Müller's arrest was issued.
Title: Ratcliff Highway murders
Content:  On 24 December, more than two weeks after the Marr family had been murdered and five days after the killing of the Williamson family, the maul was identified as belonging to a sailor named John Petersen, who was away at sea. The information was volunteered by a Mr Vermiloe, the landlord of The Pear Tree, who was incarcerated in Newgate Prison for debt. Constables searched the premises and found Petersen's trunk, which was missing a maul. Vermiloe recalled that not only had the maul been in the chest, but that he himself had used it and was responsible for chipping it. That was a significant lead. It has been noted that the substantial reward money for information 
Title: Gustav Müller (serial killer)
Content:  In March 1893, Müller boarderd a ship from India towards England, passing through France on the way. The penniless watchmaker landed at Dover, and at the end of March, he found himself in London. A police constable named Ridgway found the man wandering around Southwark on March 30, taking Müller to the St. George's Workhouse on Mint Street. There, Müller, speaking in German because he didn't know or understand English, explained to the doctor various fascinating tales, as well as professing that he butchered his parents, wife and several children. Most peculiarly, at times he even claimed that he had killed over 4,000 people, 
Title: Michael Lupo
Content:  On 15 March 1986, the body of a 37-year-old murder victim named James Burns, a railway worker originally from Edinburgh, was found in a derelict flat in Kensington, London. The investigation did not make much progress because there was no obvious link between a perpetrator and the dead man. On 6 April that year, the corpse of Anthony Connolly, 24, was found on a railway embankment in Brixton. He had been strangled with his own scarf. Because Connolly had been sharing a flat with a man who was HIV positive, there was a long delay between the discovery of the body and the post mortem because the coroner wanted to make sure Connolly was not himself infected with HIV. This created serious tensions between the authorities and the gay community, the latter accusing the former of dragging their heels and not taking the death of a gay man seriously enough.
Title: Bob Woolmer
Content:  had died of natural causes, and was not murdered as indicated by the earlier pathologist's report. Three independent pathologists' reports commissioned by the police had found that the initial conclusion of manual strangulation was incorrect, and toxicology tests found no evidence of poisoning. The findings of the pathologists, and of Metropolitan Police detectives who had visited Jamaica to assist with the investigation, were reported in the weeks leading up to the announcement, which was widely expected by the time it was made. Reports suggested that Woolmer suffered from health problems including an enlarged heart and diabetes, which may have contributed to his death. On 6 November, coroner Patrick Murphy asked for further tests to be carried out on samples 

Question: when did we find out the smoking man was mulder's father?
Answer: Later in the sixth season.
in the sixth season.