A man has been jailed for life for the murder of two pensioners in their own homes more than 20 years ago under the double jeopardy law.

Michael Weir killed Leonard Harris, 78, and Rose Seferian, 83, during the robberies in 1998, leaving them both for dead.

Weir stole a signet ring and gold watch from Harris’s property in east Finchley, north London, and nearly two months later ripped diamond rings from Seferian’s fingers at her flat in Kensington, west London.

The case is believed to be a legal first of a defendant convicted twice for the same offence after an acquittal in the court of appeal. It is also unique because he faced a second murder charge in addition to the original murder.

The two deaths were not linked at the time after police failed to match Weir’s palm print to one recovered from the Harris home in 1998.

Weir was convicted of Harris’s murder, burglary and the attack on Harris in 1999 but his conviction was quashed on a technicality in 2000. He was tried for Seferian’s killing after new forensic evidence emerged and was retried for Harris’ murder after a change to the double jeopardy law.

Jailing Weir for life with a minimum term of 30 years, Mrs Justice McGowan said: “For the families, it’s impossible to understand the extent of their grief but it is not difficult to understand their sense of loss and outrage. You killed their parents, they died terrified - killed for items of jewellery.”

A jury at the Old Bailey found him guilty of both murders last month.

On 28 January 1998, Weir broke into Harris’s north London flat. The victim was found by an estate agent calling for help from the communal landing and his widow, Gertrude, also sustained head injuries. She died several years later in a care home.

An 18-carat gold Zenith watch that Harris had taken from a German soldier during the second world war and his gold ring were missing.

Three days after the attack, police found a palm print on the bedroom door but missed the match to the defendant at the time because a comparative print was not the best quality, the jury heard.

Prosecutor Tom Little QC said the evidence of the print definitely put Weir in the victim’s flat, right by the scene of the attack on Harris.

DNA testing, not available in 1998, later also linked Weir to the crime scene. A blood scraping from the internal hallway revealed DNA belonging to both Harris and the defendant. A glove stained with blood was found on a grass verge outside the flat and also found to have the defendant’s DNA on it.

On 5 March 1998, Weir assaulted Seferian in her bedroom when she was home alone and stole rings and cash. The jewellery included a gold wedding ring with her husband’s initials and the date of their marriage engraved on it, a diamond solitaire gold ring, and a silver diamond ring.

Seferian managed to raise the alarm and her son found her covered in blood and “almost unrecognisable” from her injuries.

A palm print was recovered from inside Seferian’s flat on a window frame where Weir broke in but it was not matched to the defendant until 2017. By 2018, the new DNA evidence in the Harris murder had been obtained and the palm prints from both scenes had been matched to the defendant.

In his evidence, Weir denied ever being at Harris’s flat or Seferian’s home and provided no explanation for the forensic evidence.

After the verdict, Justice McGowan told jurors they had “made legal history”. They were told the first case against Weir for Harris’s murder was built on DNA erroneously kept on the police database. The original trial judge had ruled it was admissible but that decision was overturned by appeal judges and Weir’s conviction was quashed.

The Crown Prosecution Service (CPS) missed a deadline to appeal to the House of Lords by a day. But the Lords later found that, in a similar case as well as Weir’s, the original decision to admit the DNA was correct.

Weir was charged again over Harris’s death due to a change in the double jeopardy law in 2005.

Jill Harris, Harris daughter-in-law, said the family felt “let down by the criminal justice system” for the errors that led to Weir’s first conviction being quashed and the CPS’s failure to make an appeal in time.

She said her husband, Frank, had suffered a stroke that doctors believed was linked to the stress of the retrial process.

Seferian’s daughter, Sona, said in a statement: “The defendant has been allowed to get on with his life for 21 years. Our wound is still sore and it has never healed. We all know death will strike at some point but not in such a horrific and senseless way.”