Tag experiment criminals reoffend

And around a quarter of them committed fresh crimes while being tracked, including one who was jailed for life and two others who received indeterminate sentences for "very serious offences", research for the Ministry of Justice has found. But the researchers also discovered evidence that the hi-tech tracking system helped convict some offenders, as well as keeping others out of trouble.

Some 336 people in Greater Manchester, Hampshire and the West Midlands took part in trials of the new technology between 2004 and 2006 - most of them prolific offenders, including many convicted of sexual and violent crimes.

The pilots were targeted at offenders deemed to be "high risk", with records of repeat convictions. A majority of those tracked had been released on licence after serving time in prison, though some had been given community penalties for less serious crimes.

The offenders had to wear ankle tags and carry a portable tracking unit, which allowed their movements to be tracked via Global Positioning Satellite (GPS) technology. In some cases, the system allowed police to be alerted if offenders entered exclusion zones which they had been ordered to avoid.

When the pilots were launched in 2004, ministers said the tracking devices would help to deter offenders from breaking the law, as well as allowing swift intervention if restrictions were flouted.

But the report by Birmingham University criminologist Prof Stephen Shute found that in most cases, a system of "passive tracking" was used which meant it could be 24 hours before police and probation were alerted to breaches.

The report revealed that a total of 194 of the tagged offenders (58%) were either recalled to prison for breaching their licences or had community penalties revoked during the period they were ordered to be satellite-tracked.

Some 70 individuals (21% of the total) were convicted of offences committed during the period they were being tracked and 42 were jailed for them, while a further 16 (5%) were considered by probation officers to have committed offences while tagged. Of 149 who were recalled, 48 removed their tags and went on the run - with one remaining unlawfully at large for 233 days.

One individual committed a very serious offence for which he received life imprisonment while being tracked, and two others received indeterminate prison sentences for public protection for offences committed while on the run.