The trial – the accuser became accused
Kastner was a civil servant; therefore, the Attorney General at that time Haim Cohen, decided to blame Gruenwald for libel. Shmuel Tamir, Gruenwald's lawyer, a prominent political figure and a minister in the Israeli government defended Gruenwald and was able to side track the trial – from a libel case to an arraignment campaign ─ against Kastner who turned from an accuser to an accused.
In June 1955, Gruenwald was acquitted of most charges and Kastner was given a bad name. District Court Judge of Jerusalem, Dr. Benjamin Halevi wrote a sentence that was engraved in the public's memory: "Kastner sold his soul to the devil". Kastner filed an appeal and in the beginning of 1958 after his death, he was acquitted of most charges.
The murder case solution
On March 3-4 1957, minutes after midnight, upon his arrival to his home in Tel Aviv, Kastner was shot and critically injured. Two weeks after the incident he died of his injuries. The shooter jumped off a Jeep that parked near the house. He approached Kastner who was locking his car, asked him if he is Kastner, and when the latter answered positively, he pulled out a handgun and shot him.
The first bullet was a spent bullet, the second hit the car's door, and the third hit the upper part of Kastner's body; Kastner tried to escape but was critically injured. The shooter returned to his Jeep and quickly drove away from the scene.
About an hour after the shooting, ISA began concentrating its efforts in order to reveal details of the assassination. The efforts focused on a grouping led by two of LEHI veterans: Yosef Menkes and Yaacov Heruti whose people were linked to various murder incidents and different lines of action against Kastner. They assumed that Menkes was personally involved in the assassination.
That night alone, Menkes and six young men, affiliated with the grouping, were arrested; as their description matched that delivered by Kastner at the hospital. After a short investigation, five of the detainees were released; but Menkes and Zeev Eckstein remained imprisoned since their alibi was not airtight enough. Assuming the shooter did not act alone, another examination of the information was conducted and Dan Shemer was among the potential suspects. Shemer was arrested; he confirmed his acquaintanceship with Eckstein since both were IDF paratroopers and met several times close to the incident.
The assistance of eye witnesses enabled the police to track down the Jeep which parked near Kastner's home the night of the shooting. In it was found the handgun used by the shooter, and fingerprints which matched those of Dan Shemer.
On March 7, Shemer disclosed his involvement in the assassination. He was the driver of the Jeep and Zeev Eckstein was the shooter. He even reenacted his and Eckstein's driving course on the night of the assassination.
The investigator took Eckstein for a ride in Tel Aviv promising not to present a single question while driving in order to convince Eckstein to confess as well. The investigator drove according to Eckstein's and Shemer's driving course on the night of the assassination, pointed at places and described Eckstein's actions as was noted in Shemer's confession. Towards the end of the ride, the investigator lingered near Shemer's home and told Eckstein: "Here lives your friend whom you've turned into a criminal".
Eckstein said nothing but later on he asked to meet again with the investigator and told him: "I was guilt-ridden when you made your remark near Dan Shemer's house". Eckstein said he wanted to confess and told that Menkes was the one to give him the handgun and ammunition, and solicited him. Over the next few days he reenacted the assassination near Kastner's house and wrote a detailed confession. In the confession, he revealed step by step that Menkes led him to execute the assassination.
Following Eckstein's confession, it was decided to arrest more of Menkes-Heruti group members, including Heruti himself. The number of detainees reached more than twenty. As a result of their investigations, two weapons magazines were exposed which belonged to the grouping.
On March 15, 1957, Kastner died of his injuries. Eckstein, Shemer, and Menkes were charged with murder and violations of the Prevention of Terrorism Ordinance. Menkes was charged for directing a terrorist organization, and Eckstein and Shemer were charged for membership in a terrorist organization. In court Shemer and Eckstein repeated their confessions but Menkes did not cooperate with his investigators and pleaded not guilty; he blamed the ISA in committing the murder and conducting a show trial against him.
Eckstein was convicted as the main executer of the murder, and Shemer as his facilitator. The court determined Menkes solicited Eckstein to murder Kastner and provided the weapons and ammunition. Therefore, he was convicted as a copartner, a solicitor, and a facilitator of the murder. The three were sentenced for life but were granted pardon and in 1963 they were released early from prison.
Kastner's murder and the trial which followed it generated a public interest of the ISA and proclaimed its existence which until then was kept secret and even denied. For the first time, the exposure led to a parliamentary supervision of ISA. The quick capture of the perpetrators, the legal handling of the case, and the sentences imposed sent an unequivocal message: the existence of a violent underground group in Israel is unbearable. This message permeated all social classes and led to a long period which lacked radical and intensive activity both from right and left wing elements as well as lack of underground groups.