G4S’ involvement in Israel’s occupation of Palestine is manifold. A Who Profits report , "The Case of G4S: Private Security Companies and the Israeli Occupation," lays out G4S's involvement in the occupation, where these pictures and much of the information below comes from.
Israeli prisons hold a large number of Palestinian political prisoners. According to Addameer , the Prisoner Support and Human Rights Association in Palestine, most Palestinian prisoners are held in detention facilities located outside the oPt. However, the transfer of detainees to locations within an occupying power’s territory is illegal under international law and can be constituted as a war crime. As Article 76  of the Fourth Geneva Convention states, “Protected persons accused of offenses shall be detained in the occupied country, and if convicted they shall serve their sentences therein.” As of October 2012, the current documented  Palestinian political prisoner population in Israeli prisons and detention centers was 4,596 people, including women, children and hundreds of administrative detainees. Administrative detention is a procedure that allows the Israeli military to hold prisoners indefinitely for renewable 6-month periods on secret information without charging them or allowing them to stand trial.
A main prison facility for Palestinian political prisoners is the Ofer compound in the West Bank. G4S Technologies provided a perimeter defense system for the walls of the Ofer and installed a central command room inside to monitor the entire facility. Despite being in the West Bank, the compound is located in what Israel defines as the “Seam Zone,” on the Jerusalem-Ramallah road, making access for West Bank Palestinians highly restricted, both for family members of detainees and for their lawyers. Entry is dependent on the receipt of a special access permit, also making it nearly impossible for the Palestinian public to attend court hearings.
Additionally, G4S has provided security systems for several other detention facilities and prisons that hold “security prisoners” (ie Palestinian political prisoners) from both Israel and the oPt. Human rights and prisoner rights organizations in Israel have documented  cases of torture and abuse of Palestinian prisoners at several of these facilities and petitions, such as this one  (Hebrew), have been submitted on behalf of Palestinian plaintiffs testifying that they have undergone torture. Palestinian detainees who are interrogated in these detention facilities report being shackled in painful positions for days, deprived of sleep, denied medical care, beaten, and exposed to extreme temperatures for long periods of time. Additionally, detainees report undergoing psychological torture, including being threatened that if they do not confess, close family members will be brought in for interrogation and torture, that they will be imprisoned for long periods of time, and/or that their homes will be demolished. A report  by Defence for Children International – Palestine Section (DCI Palestine), highlights how children are also arrested, detained, and mistreated at these prisons, even documenting cases of torture at these facilities. It has also been recorded that children may not receive adequate food, water, shelter, or medical services, or be able to communicate with their families. This article  highlights how children have been held in solitary confinement in prisons where G4S operates.
G4S Israel has supplied luggage scanning equipment and full body scanners to several checkpoints  in the West Bank, including the Qalandia checkpoint, the Bethlehem checkpoint, and the Irtah (Sha’ar Efraim) checkpoint. The Qalandia and Bethlehem checkpoints are part of the Israeli system of control that sustains its annexation of East Jerusalem, since they prevent Palestinian residents of the West Bank from entering vast areas of occupied land around the city of Jerusalem and from entering occupied East Jerusalem itself. The annexation of East Jerusalem was found to be one of the grave breaches of international law against the Palestinian people during the Barcelona session  of the Russell Tribunal on Palestine.
G4S Israel has also provided full body scanners to the Erez checkpoint in Gaza. The Erez checkpoint serves as part of the Israeli closure policy over the Gaza Strip.
G4S openly offers its security services to businesses in the illegal settlements  in the West Bank and the settlement neighborhoods of East Jerusalem. In July of 2010, G4S Israel announced its take-over of Aminut Moked Artzi, one of the oldest private security companies in Israel and which provided security services to businesses in the Barkan industrial zone. G4S stated that it would continue the Aminut business operations. G4S Israel has also provided security equipment for the Judea and Samaria Police Department, Israeli police headquarters in the West Bank. This is a civilian force that polices the Israeli settler population in the segregated West Bank; their headquarters are located near the settlement of Ma’ale Adumim.