A total of 22 defendants will stand trial for murder of Sinan Ateş, a prominent nationalist figure, in the first hearing set to be held in the capital Ankara on Monday. Chairs of all major opposition parties are expected to attend the hearing they tried to link to the party Ateş once served.

Ateş, an academic, was the former head of the Idealists’ Hearths, a nationwide organization affiliated with the Nationalist Movement Party (MHP). He was murdered in broad daylight on Dec. 22 in the capital while he was walking next to a relative, who survived the attack. Ateş’s assassin was captured and is among the defendants who will be tried on charges of aiding and abetting the murder and orchestrating it. The murder suspect has told investigators that he only tried to injure Ateş over a personal feud.

Suspects were largely associated with the MHP and Ateş’s wife has also claimed that it was a larger conspiracy by party members against her late husband. The MHP repeatedly denied allegations that party members were involved in the murder, while other parties, particularly its main rival Republican People’s Party (CHP) implied the party’s plot against Ateş whose tenure as head of the Hearths ended long before the murder after he fell out with fellow Idealists.

CHP leader Özgür Özel is expected to join the head of the Good Party (IP) (which is formed by former members of MHP), as well as his predecessor Kemal Kılıçdaroğlu in the courtroom where they will watch the hearing. Suspects will be tried in a heavily guarded courthouse within a massive prison-courthouse complex in Ankara’s Sincan district where terror suspects are incarcerated.

Last week, MHP leader Devlet Bahçeli announced that they would dispatch the party’s lawyers to the hearing. "Let us see what everyone has to say, let’s see who will present what they have (against us)," Bahçeli challenged "those seeking to associate our party and the Hearths" with the murder. Prior to the hearing, Ateş’s wife Ayşe Ateş, who met President Recep Tayyip Erdoğan recently to discuss the trial, said in a social media post that the hearing would either be "a beginning or an end."

The indictment by prosecutors says the assassin E.Ö. should be sentenced to aggravated life imprisonment, along with V.B. and S.K. who took him to the site of the murder and helped him escape afterward. Others in the indictment whose prosecutors ask for aggravated life imprisonment are D.Ç., who is accused of arranging the murder, and T.B., a former Hearths member.