Following a joint investigation by Thames Valley Police and Gloucestershire Constabulary, two people were convicted of the manslaughter of two men and further poisonings today (24/6).

At the start of their trial at Oxford Crown Court, Adina Mihai, aged 31, and Madalin Dumitru, aged 30, both formerly of Ilford, Essex, pleaded guilty to two counts each of manslaughter and counts administering poison.

The pair were remanded in custody and are due to be sentenced on a date to be determined later this year. The judge said they will receive substantial terms of imprisonment.

Between August 2024 and July 2025, Mihai and Dumitru targeted men, who had been seeking sexual services.

The pair took financial deposits from the victims before Mihai met them at their homes. They secretly spiked their drinks with GBL – a substance that converts into GHB when in the body – to render them unconscious and steal from them.

Two of those men; Gary Mouat, aged 37 and from Banbury, and Malcolm King, aged 80 and from Bagendon, near Cirencester, sadly died.

Gary was found dead at his property in Banbury, on 13 July last year.

Once Thames Valley Police detectives discovered Mihai had poisoned Gary, the force issued a national bulletin to all other police forces to share the intelligence in case any other unexplained deaths in the country were linked.

Forensic links led to Gloucestershire Constabulary discovering Malcolm had also been poisoned, after initially believing his death on 21 August 2024 was not suspicious, due to a pre-existing health condition.

Mihai and Dumitru were arrested on 31 July last year and charged on 6 August last year, in relation to Gary’s death.

The pair were further charged in relation to Malcolm’s death, on 24 April this year.

Thames Valley Police senior investigating officer, Detective Inspector Michael Roddy, of the Major Crime Unit, said: “This has been an extremely complex and resource‑intensive investigation, involving specialist teams across Thames Valley Police, Gloucestershire Constabulary and partner agencies so I am proud to have this positive result.

“Adina Mihai and Madalin Dumitru used drugs to incapacitate men who had been seeking sexual services, before stealing from them.

“For Gary Mouat, these actions had fatal consequences so I am pleased to have got answers for his family and would like to thank them for their support throughout our investigation.”

Gloucestershire Constabulary’s senior investigating officer, Detective Inspector Adam Stacey, of their Major Crime Investigation Unit, said: “Tragically for Mr. King, Mihai and Dumitru’s callous and calculated actions had fatal consequences.

“The tireless work of all those involved in the joint investigation left Mihai and Dumitru with little choice but to plead guilty to manslaughter and administering poison in the face of overwhelming evidence.

“Our thoughts are with Mr. King’s family, at what must remain an incredibly difficult time for them. We continue to support them with our specialist officers.”