Barrena was born on 1 November 1965 in Pamplona, Navarre.[1] His father José María Barrena Inza was a socialist mayor of Berriozar.[2][3] He has Técnico Superior qualification in international trade and a degree in international relations from UOC.[4]
In 2001 Barrena became a member of the national executive of the newly formed Batasuna, the successor to HB which had been dissolved.[9]
He was the lead candidate at the 2003 regional election in Navarre for the Autodeterminaziorako Bilgunea (AuB) electoral alliance but the Supreme Court annulled the list as it considered AuB to be a successor to Batasuna which had been banned in March 2003.[2]
Following the death of two ETA prisoners, Igor Angulo Iturrate and Roberto Sainz del Olmo, Basque nationalists, who did not believe the official version of the deaths given by the Spanish government and instead believed they died because of tortures suffered after their arrests,[10][11] organised a strike in March 2006. All demonstrations were banned by the Basque government.[12] Thid resulted in clashes between protesters and the Ertzaintza police across the Southern Basque Country.[12][2] Barrena and other leaders of Batasuna were arrested on the orders of judge Fernando Grande-Marlaska who held them responsible for attacks by the strikers.[5][13] Barrena was released after paying a bail of €200,000, but the charges were ultimately dropped, as no links between the two could be proven.[5]
Barrena was a candidate at the 2007 regional election in Navarre for the Nafarroako Abertzale Sozialistak electoral alliance which was also annulled by the Supreme Court.[2] On 4 February 2008 a conference was held at the Hotel Tres Reyes, Pamplona involving Batasuna, Basque Nationalist Party and Socialist Party of the Basque Country–Basque Country Left which was attended by Batasuna leaders Barrena, Patxi Urrutia and Unai Fano.[14][15] Barrena and Urrutia were arrested on 4 February 2008 on the orders of judge Baltasar Garzón for "supporting the activity of an illegal political party".[7] Barrena was released on 3 February 2010 after paying a bail of €50,000.[16]