The convicted ETA killer whose early release has caused an outcry

Madrid wasn't a safe city when Antonio Troitiño Arranz was on the loose in the 1980s.

As one of the most dangerous members of ETA, Troitiño had chalked up 22 killings before he was busted. So when a legal loophole allowed the now 53-year-old terrorist an early release from prison this week, there was an outburst of disapproval from most of the country's political and social sectors.

Troitiño, also known as Miguel Ángel or "Antxon," had been in custody since January 16, 1987, when he was arrested along with others in connection with the bombing at the Republica Dominicana square in Madrid. Twelve civil guards were killed and 58 people seriously injured in the bloody incident, carried out by ETA's "Madrid commando unit" on July 14, 1986. It involved seven other members of the Basque terrorist group, including its most infamous member José Iñaki de Juana Chaos. It was ETA's boldest attack in the capital.

Troitiño was the one who pushed the button on the remote detonator that set off the bombs, which had been placed in a van. He did so just as the Civil Guard officers were passing by on a bus. In 1989, the High Court gave him the maximum sentence for the incident: 2,232 years in prison.

Troitiño's violent streak runs in the family. His brother Domingo, now 55, is serving a more than 760-year sentence for masterminding the 1987 bombing at a Hipercor supermarket in Barcelona. That incident, which left 21 people dead and 45 injured, is considered ETA's bloodiest attack ever.

Troitiño's nephew, Jon Joseba Troitiño Ciria - Domingo's son, who was only six when his uncle set off the Plaza Republica Dominicana bomb - also joined ETA, rising through the ranks to become a lieutenant to the group's military leader Garikoitz "Txeroki" Aspiazu, who was captured in 2008. Troitiño Ciria fled to France after the Civil Guard fingered him as the main suspect in a string of hotel bombings in Benidorm and Alicante in 2003, which injured more than a dozen people. The 31-year-old nephew has been sitting in a Spanish jail since last July, when he was turned over by French authorities, who arrested him in 2005.

But Antonio Troitiño is the only jailed member of his family able to see the light of day, despite being pinned with two dozen murders.

He had been serving his time at a prison in Huelva, Andalusia, far from his native Tariego de Carrato in Palencia, when he received word late on Wednesday that he would be released. Dozens of people holding the Basque national flag waited for him as he emerged from the high-walled compound.

Carrying only a small bag, Troitiño was greeted by several family members, including a small boy. He embraced a woman and a man and acknowledged the supporters, kept at bay by police, with a clenched fist, and then applauded them before jumping into a taxi and speeding away.

Troitiño was not due to complete his sentences until 2017, but his early release came from the Constitutional Court's controversial ruling in 2008 that allowed inmates to earn credit on their entire sentence in one case by counting the days they also spent in preventive custody awaiting sentencing in other cases. In effect, Troitiño served 24 of the maximum 30 years that he can be held under Spanish law.

Under that doctrine, numerous drug traffickers, terrorists and other dangerous felons have benefited from early release.

Last December, the government modified the Penal Code to allow inmates to tack on the time they have been held before sentencing, only to earn time-served-credit for that particular case.

Before the Civil Guard massacre, Troitiño had a hand in a string of other killings. On June 12, 1985, he helped plan and participate in an attack on an army colonel and his driver in Madrid. Less than two months later, he also murdered deputy Admiral Fausto Escriga, and on April 25, 1986 he was part of the ETA team that planted a car bomb that went off on the corner of Príncipe de Vergara and Juan Bravo, which killed five Civil Guard officers and injured 11 people. In 1990, the High Court sentenced him to 378 years in prison for this attack.

In June that same year, his unit helped plan the ambush of army Lieutenant Colonel Carlos Vesteiro, Commander Ricardo Sáenz and Private Francisco Casillas, who were all gunned down by three ETA hitmen. Troitiño was waiting in a stolen getaway car.

Prosecutors said on Thursday that they will ask the High Court to revoke Troitiño's early release order and send him back to prison.