A corrupt solicitor who was at the heart of a criminal network that made multimillion-pound profits from the heroin trade will be jailed today.

Naveen Sagar laundered drug money, orchestrated false defences and supplied bogus witnesses to help major criminals to evade justice. He was involved directly in fraud and burglary and was suspected of trying to derail an Old Bailey murder case after police found a picture of the trial jury on his mobile phone.

Sagar flaunted the proceeds of his corruption – wearing designer suits, driving a Porsche 911 and buying a portfolio of properties – until Ahmed Osman Hersi, a Somali-born drug dealer, gave evidence against his former solicitor and other criminal associates in an attempt to earn a lighter sentence for himself.

Sagar, 32, will be sentenced at Kingston upon Thames Crown Court after pleading guilty to perverting the course of justice, fraud, contempt of court and burglary. Police have obtained an order to confiscate assets valued at more than £1 million.

Hersi, 29, who arrived in Britain as a refugee in 1983, will be jailed tomorrow having pleaded guilty to possessing firearms with intent, possessing Class A drugs, perverting the course of justice and handling stolen goods.

The pair were caught after a three-year investigation by the serious and organised crime division at Scotland Yard. Detectives admit that they are unlikely to trace millions of pounds that have been transferred to offshore accounts. Detective Chief Inspector Peter Beyer told The Times: “We know the money has gone worldwide. This gang controlled a large part of the drug trade in London, it was a multi-million-pound business. They were very astute, always thinking about how to launder the money.”

The inquiry began in October 2004 when Hersi was arrested after becoming involved in a road-rage incident with a bus driver. In the boot of his Mercedes, officers found £32,000 in cash.

Hersi called Sagar, who arrived at a police station with a prepared defence and a witness who claimed that the cash belonged to him. Although inquiries showed the notes to be coated with heroin, police were forced to return the money to Hersi. Inquiries revealed that Sagar, who came from a respected Indian business family, received £5,000 for his part in the deception. His witness, Muhammad Azam, was paid £7,000.

In January 2005 officers saw Hersi and three other men buying and selling firearms in Hackney, East London. PC Chris Brodie managed to grab a gun but the men escaped despite crashing their Porsche. Three men – Yusef Farah, Jama Ahmed and Olaniyi Olowayie – were arrested at later dates and were jailed after Hersi gave evidence against them.

Hersi came under the spotlight again in April 2005 when a security guard at McDonald’s in Leicester Square, Central London, reported what he thought was a drug deal in progress. Hersi had been buying two Mac10 machineguns and left a West End nightclub – where he had been attending an invitation-only party for the Professional Footballers’ Association – to complete the deal. The guns were recovered from the boot of a chauffeur-driven Mercedes.

Hersi was arrested in a police raid in February last year and was found to have £29,000 cash. Again he called Sagar, who produced Azam with another claim that he had legal entitle-ment to the cash. But when Azam was told that the money was impregnated with traces of heroin, he admitted to police that he had agreed to help Sagar to provide false defences for Hersi.

Another witness did the same and, in February last year, Sagar was arrested in a police raid. Under his bed was £85,000 in cash and an emergency services radio scanner tuned into police channels. On his computer were a series of recordings of interviews with a witness that had been doctored to create the impression that officers were acting in a corrupt manner.

Sagar’s firm, Mehra & Co, was shown to have been defrauding legal aid fees by setting up a bogus interpreters agency. The firm has closed down and his partner has received a suspended jail term for fraud. Sagar’s practising certificate has been withdrawn and he will be struck off formally by the Law Society after he is sentenced.

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