However, police didn't confirm Memon's presence in London.
Police feel that Iqbal Mirchi, close aide of underworld don Dawood Ibrahim who was recently arrested would help investigators to find out if Dey had met Memon in London.
"Our probe indicates that Dey might have met Memon in London during his visit in April. Chhota Rajan thought that Dey had provided some information about him to Dawood's aide Memon and ordered his killing," said an official.
Memon's extradition would not only help the investigator to probe journalist's murder case but also the activities of Dawood in other countries, said the crime branch official.
Dey who headed the special investigative team from MiD-DAY newspaper, Mumbai, was killed on Saturday, Jun 11, by few unidentified bike-borne assailants. He was shot dead by firing five bullets.
Dey was working on an oil mafia article. It was being suspected that probably the oil mafia head was behind murder.