However, the project was seized in 3643 BBY by Lord Nefarid, an apprentice of Darth Angral. Angral, who was seeking revenge on the unknown Jedi Knight who had killed his son Tarnis, had his apprentices take control of several of the Republic's superweapon projects in order to build his own. The Knight, however, arrived on the planet and was able to destroy the Death Mark laser, killing Nefarid in the process.
The Death Mark laser superweapon consisted of an orbital platform that was able to fire highly accurate beams of super-concentrated energy at a specific individual. This fatal beam was able to penetrate virtually any structure or shield, making escape impossible. However, the unknown Jedi Knight who destroyed the Death Mark laser was able to evade the weapon's attacks, as the Jedi's danger sense enabled the Knight to leap out of the path of the orbital attack.
The weapon targeted individuals through the use of a special targeting device, which marked targets with a microscopic tag. The targeting mechanism was only effective at extremely close range, which meant that an operative needed to get within at least twenty meters of an intended target in order to use it. The mark was virtually undetectable, and marked individuals could be tracked indefinitely.
The Death Mark laser was intended for use in ending the Alderaan Civil War, as the lives of hundreds of soldiers and civilians could be saved by targeting key enemy leaders. Such a tactic would have lead to their elimination without the use of armies or bring about the risk of collateral damage. However, in the wrong hands, the Death Mark laser was equally capable of being used as a weapon of terror and rain down murder from the sky on selected targets—which is the exact use that it was put to by the Sith apprentice Nefarid.
The Death Mark laser project was begun by the Galactic Republic during the Cold War with the Sith Empire. The Republic decided to base the project on the Core World of Alderaan, which was in the middle of a brutal civil war over which house would take the throne, because the weapon had the potential to end the war quickly and without massive loss of life by targeting enemy leaders.
However, in 3643 BBY, an unknown Jedi Knight killed Tarnis, the son of the Sith Lord Darth Angral. This drove Angral to seize control of several Republic superweapon projects, including the Shock Drum, Power Guard Project, and the Planet Prison technology that his son had invented. Angral intended to combine the technology of these weapons with his Harrower-class dreadnought Oppressor, which he would then use against the Jedi homeworld of Tython to gain revenge upon the Knight.
Angral sent one of his apprentices, Lord Nefarid, to Alderaan to take control of the Death Mark laser. Nefarid and his Imperial forces stormed the Death Mark laser facility in the Mensaav Military Laboratory in the Alsakan Lowlands, killing the lab's security forces. However, Jedi Master Orgus Din (the master of the same Knight who killed Tarnis) arrived and drove back the Sith attackers, forcing Nefarid to summon the insectoid native Killiks as reinforcements. The Imperial spy Aleyna Hark "escaped" the facility and traveled to Organa Palace, where she met with the project's benefactor Count Alde.
However, the unknown Knight arrived and met with Alde at the same time, causing Hark to lie and say that Din was dead. She had also marked the Count with the Death Mark laser's targeting device, allowing Nefarid to kill Alde in the middle of their conversation. The guards rushed in after hearing the commotion, and Guard Captain Yils attempted to arrest Hark, the Knight, and the Knight's companion when he found the Count dead on the floor. Hark offered herself in the Knight's place, asking the captain to let the Jedi complete their mission, and was taken away by the guards. However, she never made it to her cell—she killed the guards and began marking targets throughout the Palace.
The Jedi, meanwhile, fought their way through the Killik-infested lab and discovered the Knight's master alive in a sealed room with Doctor Parvux, the only scientist that Din was able to save. After Din and his former Padawan defeated the massive Killik Praetor, Parvux suggested shutting down three of the Death Mark laser's generators to disable the laser temporarily. But while the Knight was doing so, Nefarid contacted the Jedi and informed them that he had set up another power station beyond their reach.
Conferring with Din, the Knight decided to pursue Aleyna Hark, who Parvux had revealed to be a spy, to a compound of House Thul. House Thul was an ally of the Empire, but their duke Horis Thul supported House Organa's peace talks, and the peace process would fall apart if Thul was killed by a Republic superweapon. The Knight raced to the Thul compound and found Aleyna and the Duke, and after defeating the guards Hark ordered to attack the Jedi managed to convince Thul that Hark was acting against him. Hark destroyed the targeting device, however, and told the two that they had both been marked. After knocking out the spy, the Duke told the Knight where he had tracked Nefarid and fled the planet.
The Jedi then stormed Nefarid's base in the Glarus Valley, eliminating the Imperial troops within. The Jedi was then shown a hologram of Angral killing Orgus Din aboard the Sith's ship, as the Knight's master had sneaked aboard to eliminate Angral. Nefarid then attacked the Jedi, using the Death Mark laser as a weapon during their duel. However, the Knight and their companion managed to defeat the Sith, and used the Death Mark laser's targeting computer to destroy the computer itself, rendering the satellite useless. Some members of the project survived to join the Cult of the Screaming Blade.
The Death Mark laser was created for Star Wars: The Old Republic, a massively multiplayer online role-playing game released by BioWare on December 20, 2011. It serves as the main objective of the Jedi Knight class storyline on Alderaan, and it is destroyed at the culmination of the planet's quests.