Detectives are investigating the death of the DJ Kevin Greening and have arrested a man on suspicion of supplying Class A drugs at the home in Wandsworth, south London, where the former Radio 1 presenter died in his sleep on Saturday night.

The man, who is in his 50s, was questioned and bailed by police to return in March.

A postmortem examination conducted at St George's hospital yesterday was inconclusive, prompting police investigators to classify Greening's death as "unexplained". The inquiry into the death has been handed to detectives at the Specialist Crime Directorate at Sutton, a unit normally charged with investigating the capital's most high profile and serious cases. The transfer is not, however, an indication that a murder inquiry is under way, according to a Metropolitan police spokesman.

The arrest has raised questions over Greening's final hours. "A man was arrested at the scene in connection with the death and has subsequently been bailed on suspicion of possession with intent to supply Class A drugs, pending further inquiries," the police spokesman added.

Shortly after Greening's death a statement released by his agent, Chris North, said the popular DJ died "peacefully" in his sleep.

Greening's next of kin have been notified, although formal identification of the body is not expected until today.

Tributes have poured in since the death, with colleagues praising his talent and passion for radio.

Greening, 44, worked alongside Zoë Ball on Radio 1's morning show from 1997 to 1998. He later presented shows on BBC Radio 5 Live and most recently oversaw a weekly show on the London station Smooth Radio.

Radio 5 Live's Simon Mayo, who worked with Greening at Radio 1, told Smooth: "He had a very, very dry sense of humour and he was quite shy really, sometimes embarrassed about having achieved the level of fame that he did have.

"Anyone who listened to his programmes could tell he was extremely bright, extremely clever. He was naturally gifted."

Greening, who was gay, was part of the launch line-up of Virgin Radio in 1993. He transferred to Radio 1 within a year, hosting weekend shows and standing in on daytime slots. He became renowned for his tongue-in-cheek style and introduced comedy sketches to his programmes through a series of fictional characters.