The murder recently of Lithuanian gangster Gintaras Zelvys in Rathcoole, Co Dublin, is a further signal of the invasion of Ireland by foreign criminals involved in everything from organised begging to hi-tech crime.

They are attracted here, gardai say, by what the criminals regard as a remarkably lenient justice system and the low risk of being caught.

Zelvys was regarded as a major criminal figure. He was released from prison a year ago after serving a seven-year term for extorting money from innocent Lithuanians in Monaghan and other counties. He was also sentenced to four months' imprisonment in 2008 for assaulting a female garda in north inner Dublin. Before coming here, he had escaped from prison in Lithuania where he was serving a jail term for rape.

Zelvys also ran a lucrative trade in smuggling mobile phones and other contraband into Portlaoise Prison where he had associations with Dublin criminals. At the time of his imprisonment in 2007, he was living in Celbridge in Co Kildare and driving an €85,000 Mercedes CLS. Gardai believe Zelvys was murdered by other Lithuania mafia here.

A remarkable insight into the view of Ireland as a destination for foreign criminals was discovered by gardai in Dublin last year after they had arrested three Nigerian nationals, members of an organised mobile phone theft and drug smuggling organisation. The gardai checked the phones of the three arrested and on one, they found a text that had been sent to an associate back in Nigeria. It read: "Come to Ireland. It is a virgin country. There is plenty of money to be made."

The theft and export of expensive smartphones is a multi-million industry here. Last month, gardai issued a report calling for people to record the IMEI numbers on their phones so that they could contact their providers and stop the phones from being used in Ireland. They revealed that 8,000 phones had been reported stolen in the first six months of last year.

However, this figure does not include the number of phones that were reported as lost, but were probably stolen.

The number of phones stolen is likely to be very much higher, running into tens of thousands. The Carphone Warehouse reported in 2011 that it had received an average of 380 reports of lost or stolen phones a week, or around 20,000 a year.

Gardai say there is theft of phones from pubs and cafes across the country on an industrial scale and that there is heavy involvement of foreign criminals.

"Young people are daft. They leave their phones on bars and tables and young women leave their handbags open. What do they expect? The robbers go from pubs to cafes, cleaning out the places. Most young people don't even know their phones have been robbed and only report the phone as lost," one garda said.

He added that Ireland had been a destination of choice for foreign criminals for years and gardai were seeing no let-up in the trend. "There are hordes of them coming here. Why wouldn't they? It's a great country for a criminal."

The murder of the Lithuanian at the industrial estate in west Dublin came two weeks after RTE's Prime Time Investigates shone a light on the industrial-scale theft of second-hand clothing from Irish charities' recycling banks around the country.

Prime Time also highlighted the established scam of leafleting householders with fake charity leaflets. Of the few cases against the clothing thieves that have gone to court, none has resulted in imprisonment and instead have involved only small fines and orders under the Probation Act.

Gardai contrast the lenient treatment of foreign criminals with the huge numbers of motorists, more than 400,000 a year, who are issued with on-the-spot fines. The courts are clogged up with people unwilling or unable to pay traffic fines.

The organised begging that the Government had supposedly moved to stop two years ago with the introduction of new anti-begging legislation has been thwarted by legal challenge all the way to the High Court. Young Roma women beggars who, gardai say, are often talented pickpockets are again back on the streets in large numbers.

The male members of the Roma gypsy gangs are often involved in a wide variety of theft from ATM skimming to shoplifting and stealing scrap metal. Recently, gardai arrested three Roma men who had been using foil-lined bags to counter security tags and steal clothing from stores in Dublin. The men were carrying clothing with an estimated value of €15,000. In their car was more clothing with a similar value and at a house gardai raided they found another €30,000 worth of stolen clothing.

Two weeks ago, gardai in Dublin put on display an Aladdin's cave cache of stolen mobile phones, jewellery, clothing and other goods found in a raid on a house in north Dublin.

In the mid-range of organised foreign gangs are those targeting plant machinery, cars and marine equipment. A highly organised gang believed to include ex-soldiers from the Baltic states has been scouring harbours and marinas and stealing marine equipment for the past four years, taking everything portable from petrol containers to outboard motors and inflatable boats. Scouts posing as tourists visit the harbours and, gardai believe, log the location on GPS which they then hand over to teams of men with engineering experience who steal the equipment.

The equipment is collected and exported for sale in eastern Europe's growing, and unregulated, market for leisure boating.

Other gangs are involved in the theft and breaking of high-value cars. These gangs have electronic equipment that copies signals from keys allowing them to open the cars. They then use GSM/mobile phone jammers to block the satellite tracking signal as they drive to the yards where mechanics disassemble the cars. It is believed these gangs are part of a major network involved in exporting damaged cars from Britain to eastern Europe, where they are repaired and returned for sale in the UK.

Vietnamese and Chinese criminals are behind the network of cannabis grow-houses across the country, which have been the subject of much publicity in recent years. They choose Ireland, gardai say, specifically because our automatic right to bail means that being caught is merely an expense. The men and women tending the plants are usually in debt to gangs and are effectively slaves and regarded as disposable by the gangs.

Eastern European gangs also introduced technology new to Ireland to help them rob businesses across the country. Three years ago, gardai detected them also using mobile phone jammers to by-pass alarm systems that use land and mobile (GSM) communications to alert alarm-monitoring stations. The jammers, available now on the internet, have effectively made Ireland's 400,000 alarm systems that rely on GSM signalling, redundant.

One gang of ex-military from Kosovo and Albania was detected by gardai after an 18-month spree of robberies in the south and south-east of the country in 2010. They were using jammers to block alarm signals in dozens of late-night robberies. Gangs from the Baltic states, also ex-military, were using the same techniques to rob businesses around the country.

These forms of robberies became so common that insurance companies have been advising customers they must change their alarms to make them less vulnerable.

One Dublin security firm decided the threat from GSM blockers was growing to the extent that it has switched back to a new version of old-fashioned radio signals.

Derek Mooney, director of Action Security Services in Dublin, said the arrival and spread of the GSM blockers led his firm to introduce long-range radio signals in its alarm systems. He said: "It was eastern Europeans who brought the jammers here, the first detected in 2011. We realised that there was a need to counter that. The vast majority, 95 or 96 per cent of alarms in Ireland, use GSM and they are all vulnerable.

"It was very sophisticated eastern European gangs who began using them but our own robbers have cottoned on and they are now being used all round the country. Insurance firms are now directing big retail companies and shopping centres to upgrade."

The Minister for Justice has the authority to deport people, including EU citizens who are deemed to "act in such a way as to be a danger to public order or security". However, having a criminal record is not, in itself, grounds to be asked to leave.

However, gardai and legal sources say there seems to be relatively little effort aimed at detecting and deporting serious foreign criminals. Most of the people facing deportation who are appealing their cases to the High Court have no known criminal convictions here or abroad.

Cases before the Immigration Court in the past two years have included an Ahmadi Muslim woman from Pakistan with a Master's degree in economics and a young Nigerian woman studying accountancy in Dublin, who was deemed to have breached her asylum conditions because she had a part-time job.

The sources say that the "professional" foreign criminals simply continue committing offences after being caught and released on bail and only leave when, often after years of delays in court, they finally face imprisonment. At that point, they move to another EU country and are then free to return here when they feel safe to do so, usually with a new identity.

Irish Independent