A judge here on Monday definitively dismissed a case against an engineer accused of being Italy's elusive 'Unabomber', believed responsible for 28 attacks over the past 14 years in the Italian northeast.

Elvo Zornitta, 44, had been the only suspect in the case but investigators were never able to gather sufficient evidence against him.

The case against Zornitta fell apart in January after tests proved that a crucial piece of evidence against him had been tampered with.

A forensics expert has been placed under investigation on suspicion of altering marks left on a metal plate used in one of the bombs.

The marks were initially said to be compatible with a pair of scissors found in Zornitta's home.

Without this evidence, the prosecution presented a motion to the court asking that charges against the engineer be dropped.

''It's finally over. I can't believe it. I was afraid that something unexpected might come up at the last minute to keep the case open. It's too good to be true,'' Zornitta said after the judge's ruling on Monday.

His name first appeared in the media in connection with the bombings in August 2006 after news that he was being investigated was leaked from the prosecutor's office.

Speaking after the prosecution moved to have the case dropped, Trieste assistant prosecutor Federico Frezza speculated that Italy's 'Unabomber' was probably more than just one person, considering the fact that different explosives were used in the over two dozen attacks.

''The hypothesis that a single person carried out all the attacks is nothing more than an act of creative intuition for which there is no proof and thus it cannot be proven,'' he observed.

According to Frezza, the nature of the attacks and the types of explosives would appear to indicate that while some of the 28 attacks may have been carried out by the same person or persons, there is nothing to indicate they were all the work of the same individual.

The 28 attacks since 1994 attributed to the Unabomber involved booby-trapped devices planted explosives in beach umbrellas, cigarette lighters, eggs and tubes of tomato concentrate and mayonnaise.

Some of the bombs - such as those placed Easter eggs, felt-tipped pens and jars of chocolate spread - appear to have clearly been aimed at harming children.

In April 2003 a booby-trapped pen exploded in the hands of a nine-year-old girl who was out on a picnic with her family. The girl lost three fingers on her right hand and was blinded in her right eye.

A special pool of investigators was subsequently created to track down the serial bomber.

The work of the pool and prosecutors involved in the case has came under harsh criticism after it was discovered that evidence had been tampered with.

The Italian bomber was named 'Unabomber' after America's notorious Theodore Kaczynski who was jailed for life in 1998 after a 17-year mail-bomb campaign which killed three people and injured 29.

The American press dubbed him 'Unabomber' because he targeted universities and airlines.