A career criminal with a 44-page record and a total of 29 jail terms was locked up for another 18 months after being found in possession of heroin in prison in 2007.

A surprise raid in 39-year-old Melchior Spiteri’s cell in Division Three yielded five sachets containing 4.28 grams of heroin. There was a plastic bag with the drugs.

Four sachets and the bag were found in a packet of cigarettes in Mr Spiteri’s pocket and the fifth sachet was hidden under the mattress, the court was told.

The accused did not seem bothered about the risk of weighing sachets of drugs while in jail

The police had also found a yellow paper with a suspicious substance, which turned out to be more heroin.

Mr Spiteri claimed the drugs were for his personal use. He said he had divided the heroin, which he had bought from another inmate, to calculate how much he was consuming every day, saying it was 2.5 grams a day.

Magistrate Natasha Galea Sciberras said Mr Spiteri’s explanation was not credible because three of the sachets had the same weight – 0.05 grams – and another contained 0.06 grams.

Another 0.11 grams of the drug were in the yellow paper found.

The magistrate said the accused did not seem bothered about the risk of weighing the sachets while serving a jail term.

Psychiatrist Joseph Spiteri told the court drugs could be found in jail “left, right and centre” in 2007.

Dr Spiteri said he had known the accused since he was 16 and, since 2010, Mr Spiteri was always found clean of drugs. But upon his own admission that he occasionally smoked cannabis joints in prison, Mr Spiteri was also found guilty of having both drugs in jail.

Magistrate Galea Sciberras noted that Mr Spiteri had a voluminous criminal record spread over 44 pages and covering an array of crimes.

He had been jailed 29 times and had six conditional discharges, one suspended sentence and several fines. On nine occasions, the fines were converted into jail terms because the accused could not afford to pay.

The court said it was convinced that the sachets had the same weight because the accused planned to sell them. It seemed Mr Spiteri had kicked the habit.

She cleared him of the charge of introducing drugs into prison on grounds that he had bought them from another prisoner.

Mr Spiteri had his first brush with the law in 1990 when he was 15. Since then he has been convicted at least 59 times for crimes ranging from contraventions to violence.

Mr Spiteri’s long list of convictions include a 30-year jail term handed down in 2003 for the murder of Jason Azzopardi in Cospicua on October 22, 2001.

Mr Azzopardi had been shot at close range.