German lawmakers plan to investigate possible mistakes made by security agencies in their handling of two neo-Nazis suspected of killing a regional politician last year.

Opposition lawmakers in the central state of Hesse announced Thursday that they want to hold a parliamentary investigation into what police and domestic intelligence officials knew about the two suspects, whose trial began this week.

Stephan Ernst, a 46-year-old German man, is accused of the murder, attempted murder, serious bodily harm and firearms offenses. A second man, identified only as Markus H. because of privacy rules, is accused of accessory to murder and breaking firearms laws.

Defendant Stephan Ernst, right, who is accused of murdering politician Walter Luebcke he arrives for the first day of his trial at the Oberlandgericht Frankfurt courthouse, in Frankfurt, Germany, Tuesday, June 16, 2020. A German court will begin hearing the case against two far-right extremists accused of killing the regional politician Walter Luebcke of Merkel's Christian Democratic Union party. The execution-style slaying of Walter Luebcke shocked the country last year. Stephan Ernst a 46-year-old with previous convictions for violent anti-migrant crimes, will appear in the Frankfurt regional court accused of murder, attempted murder, serious bodily harm and firearms offenses. A second man, identified only as Markus H. due to privacy rules, is charged with accessory to murder and breaking firearms laws.  (Thomas LohnesPool via AP)

Defendant Stephan Ernst, right, who is accused of murdering politician Walter Luebcke he arrives for the first day of his trial at the Oberlandgericht Frankfurt courthouse, in Frankfurt, Germany, Tuesday, June 16, 2020. A German court will begin hearing the case against two far-right extremists accused of killing the regional politician Walter Luebcke of Merkel's Christian Democratic Union party. The execution-style slaying of Walter Luebcke shocked the country last year. Stephan Ernst a 46-year-old with previous convictions for violent anti-migrant crimes, will appear in the Frankfurt regional court accused of murder, attempted murder, serious bodily harm and firearms offenses. A second man, identified only as Markus H. due to privacy rules, is charged with accessory to murder and breaking firearms laws. (Thomas LohnesPool via AP)

Prosecutors say the men were behind the slaying last June of Walter Luebcke, a member of German Chancellor Angela Merkel's center-right Union bloc who had spoken out in favor of helping refugees. Ernst is also accused of stabbing an Iraqi asylum-seeker in January 2016.

Hesse lawmakers want to know why Ernst, who had previous convictions for violent anti-migrant crimes, had dropped off the radar of security agencies, and why they didn't intervene when Markus H., whose far-right views were also known, acquired firearms.

Frankfurt's regional court on Thursday reviewed a police video recording of Ernst confessing to Luebcke's killing following his arrest. He later retracted the confession.

Police officers lead defendant Markus H., center, into the court room in on the first day of his trial at the Oberlandgericht Frankfurt courthouse, in Frankfurt, Germany, Tuesday, June 16, 2020. A German court will begin hearing the case against two far-right extremists accused of killing the regional politician Walter Luebcke of Merkel's Christian Democratic Union party. The execution-style slaying of Walter Luebcke shocked the country last year. Stephan Ernst a 46-year-old with previous convictions for violent anti-migrant crimes, will appear in the Frankfurt regional court accused of murder, attempted murder, serious bodily harm and firearms offenses. A second man, identified only as Markus H. due to privacy rules, is charged with accessory to murder and breaking firearms laws.  (Thomas LohnesPool via AP)

Police officers lead defendant Markus H., center, into the court room in on the first day of his trial at the Oberlandgericht Frankfurt courthouse, in Frankfurt, Germany, Tuesday, June 16, 2020. A German court will begin hearing the case against two far-right extremists accused of killing the regional politician Walter Luebcke of Merkel's Christian Democratic Union party. The execution-style slaying of Walter Luebcke shocked the country last year. Stephan Ernst a 46-year-old with previous convictions for violent anti-migrant crimes, will appear in the Frankfurt regional court accused of murder, attempted murder, serious bodily harm and firearms offenses. A second man, identified only as Markus H. due to privacy rules, is charged with accessory to murder and breaking firearms laws. (Thomas LohnesPool via AP)

FILE-In this June 13, 2019 file photo a picture of Walter Luebcke stands behind his coffin during the funeral service in Kassel, Germany. German investigators have carried out raids on dozens of people suspected of posting hate messages about a regional politician from Chancellor Angela Merkel’s party who was killed last year. Walter Luebcke, who led the regional administration in the central Kassel region, was shot on June 1, 2019. (Swen Pfoertnerdpa via AP, file)

FILE-In this June 13, 2019 file photo a picture of Walter Luebcke stands behind his coffin during the funeral service in Kassel, Germany. German investigators have carried out raids on dozens of people suspected of posting hate messages about a regional politician from Chancellor Angela Merkel’s party who was killed last year. Walter Luebcke, who led the regional administration in the central Kassel region, was shot on June 1, 2019. (Swen Pfoertnerdpa via AP, file)

FILE - In this June 18, 2019 file photo, an activists of the Antifa, anti-fascism action, shows a poster of Walter Luebcke during a protest against right-wing violence in Berlin, Germany, Tuesday, June 18, 2019. German prosecutors have charged far-right extremist with the killing last year of the regional politician Walter Luebcke from Chancellor Angela Merkel’s party and a near-fatal attack on an Iraqi asylum-seeker in 2016. (AP PhotoMarkus Schreiber)

FILE - In this June 18, 2019 file photo, an activists of the Antifa, anti-fascism action, shows a poster of Walter Luebcke during a protest against right-wing violence in Berlin, Germany, Tuesday, June 18, 2019. German prosecutors have charged far-right extremist with the killing last year of the regional politician Walter Luebcke from Chancellor Angela Merkel’s party and a near-fatal attack on an Iraqi asylum-seeker in 2016. (AP PhotoMarkus Schreiber)