One of their victims – 84-year-old retired nuclear physicist Leopold Reeves – had his £74,000 life savings stolen from him.
Mr Reeves was suffering from a rare form of tongue cancer at the time of the theft and has since died.
But City of London Police obtained an international arrest warrant and he was arrested in Germany in January.
He was then extradited back to the UK in March to face his crimes.
Majewski later pleaded guilty to three fraud offences and at Inner London Crown Court on Monday, June 30, he was jailed for two-and-a-half years.
These accounts were used to “cash out” from call centre scams.
The group then cold called elderly people claiming to have been officers from the National Crime Agency.
Victims were informed that their devices were being used for criminal purposes and that they needed to transfer large amounts of money to other accounts.
Det Insp Michael O’Sullivan, from the City of London Police, said: “The victim in this case has unfortunately passed away, but we did not give up in our relentless pursuit of justice. Majewski will now answer for his crimes.
“Although this heinous act took place many years ago, we have not forgotten and will not forget victims of fraud.”
Kakumanu and Alavala, both of Admiralty Avenue in Silvertown, were sentenced to three years and two-and-a-half-years in prison respectively.
Nellikondi, of Sheffield Road in Rotherham, was given a two-year suspended sentence.
City of London Police said detectives seized around £120,000 and managed to return the majority of the stolen money to the victim at an early stage of the investigation.
