19th of April Movement The 19th of April Movement ( in Spanish : " Movimiento 19 de Abril " ) or M - 19 , was a Colombian guerrilla movement . After its demobilization it became a political party , the M - 19 Democratic Alliance ( " Alianza Democrática M - 19 " ) , or AD / M - 19 . The M - 19 traced its origins to the allegedly fraudulent presidential elections of 19 April 1970 . In those elections , the National Popular Alliance ( ANAPO ) of former military dictator Gustavo Rojas Pinilla was denied an electoral victory . The ideology of the M - 19 was a mixture of nationalistic revolutionary socialism and populism . It was inspired by other South American urban guerrilla groups , such as the Tupamaros in Uruguay and the Montoneros in Argentina . By mid - 1985 , when the number of active members was estimated at between 1 , 500 and 2 , 000 ( including a more noticeable urban presence ) , the M - 19 was the second largest guerrilla group in Colombia after the Revolutionary Armed Forces of Colombia . It had become known for carrying out a number of awe - inspiring actions that provoked conflicting feelings of amazement and anger among the different sectors of Colombian public opinion . Armed Activity . Some analysts believe that the M - 19 ' s history may be divided into two parts : the first was a failed armed revolutionary struggle during the early to mid - 1980s , while the second was a relatively constructive reincorporation into civil society and political life during the late 1980s and early 1990s . Among the actions performed by the M - 19 , some significant events stand out . In a highly symbolic action , the M - 19 stole one of Simón Bolívar ' s swords from a museum in 1974 , an event which was used by the group to symbolize what they called a civilian uprising against a regime perceived as unjust . On New Year ' s Eve 1979 , the group dug a tunnel into a Colombian Army weapons depot , taking over 5000 weapons . It was considered one of the first signs of the group ' s true potential for armed action . In February 1976 , the M - 19 kidnapped the union leader Jose Raquel Mercado , who was the president of Confederation of Workers of Colombia ( CTC ) , and on 19 April 1976 , executed him . The event shocked the country . The group accused Mercado of taking bribes and collaborating with the CIA . Dominican Republic embassy siege . The group is also recognized for other high profile activities , such as the Dominican embassy siege . The guerrillas stormed the Dominican Republic ' s embassy during a cocktail party on 27 February 1980 . They took the largest recorded number of diplomats held hostage to date in Colombia , which accounted for 14 ambassadors , including the United States ' . Eventually , after tense negotiations with the government of Julio César Turbay Ayala , the hostages were peacefully released and the hostage takers were allowed to leave the country for exile into Cuba . Some of them later returned and actively rejoined the M - 19 ' s activities . Many contemporary rumors and later accounts from the participants in this event have suggested that the Colombian government might have submitted to another of the M - 19 demands , by allegedly giving the group 1 to 2 . 5 million U . S . dollars in exchange for the release of the hostages . First Dialogues of peace . During the government of Belisario Betancur ( 1982 – 1986 ) , Jaime Bateman Cayón , by then top leader of the M - 19 , proposed a meeting in Panama with the Colombian government toward solving the conflict . But Bateman died 28 April 1983 in an airplane accident , apparently while on the way to Panama and the negotiations were suspended . The negotiations culminated with the Agreements of Corinto , The Cauca . A ceasefire was agreed , as well as the continuation of dialogue for the future demobilization of the guerrilla detachment . Nevertheless , sectors of the army opposed the agreements , as much of The Uribe as those of Corinto were responsible for attacks against the life of the main leaders ; Iván Marino Ospina , Antonio Navarro , Carlos Pizarro , Marcos Chalita , etc . Palace of Justice siege . The M - 19 , as a guerrilla group , is also recognized for the Palace of Justice siege . In this attack , on 6 November 1985 , some 300 lawyers , judges , and Supreme Court magistrates were taken hostage by 35 armed rebel commandos at the Palace of Justice , the building that houses the Supreme Court of Colombia . They demanded that president Belisario Betancur be tried by the magistrates for allegedly betraying the country ' s desire for peace . When this situation became publicly known , the Colombian Army surrounded the Palace of Justice ' s perimeter with soldiers and EE - 9 Cascavel armored reconnaissance vehicles . For a short while , unsuccessful negotiations were attempted , but they reached nowhere , despite the desperate pleas that were transmitted telephonically by some of the notable hostages involved . The Betancur administration and its council found themselves in a difficult position . They were not willing to submit to the rebels ' demands , as they allegedly considered that this would set a further precedent for the M - 19 and considerably jeopardize the government ' s position . Eventually , after tense discussions , it was decided during an emergency meeting that the military would be allowed to handle the situation and attempt to recover the Palace by force . This led to a highly controversial turn of events which , to a lesser or greater degree , continues to be debated in Colombia to this date . In the ensuing heavy crossfire between the incoming soldiers and the entrenched rebels , which included supporting gunfire from the EE - 9 Cascavels , the building was set aflame , more than 100 people died ( including 11 of the country ' s 21 Supreme Court Justices ) , and valuable legal records were destroyed . The M - 19 lost several of its top commanders during the event , and blamed the government for the ensuing bloodshed . The surviving civilian victims and their families held different positions ; some blamed the M - 19 , some blamed the Betancur administration , many blamed both . There is apparently no clear consensus on the matter . Ana Carrigan argued against the widely accepted record that drug lords , such as Pablo Escobar , may have masterminded the operation in order to get rid of several criminal investigations recorded in the documents lost during the event . A Special Commission of Inquiry , established by the Betancur government , released a June 1986 report which concluded that this could not be proven ( though it did not conclude that it was not the case either ) . Carrigan alleged that the act was a conspiracy of the Colombian government . However , her conspiracy theories and skepticism of Escobar and the Medellin Cartel ' s involvement was greatly discredited by others such as Rex Hudson , who presented overwhelming evidence linking the cartel to the plot . Former Assistant of the Colombia Attorney General , National Deputy Comptroller , Author and Professor Jose Mauricio Gaona along with Former Minister of Justice , and Ambassador to the United Kingdom , Carlos Medellín Becerra , the sons of two of the murdered Supreme Court magistrates , have pushed for further investigations into the presumed links between the M - 19 and the Medellín Cartel drug lords . Congressman Gustavo Petro , a former M - 19 guerrilla , has denied these accusations and dismissed them as based upon the inconsistent testimonies of drug lords . Petro says that the surviving members of the M - 19 do admit to their share of responsibility for the tragic events of the siege , on behalf of the entire organization , but deny any links to the drug trade . Demobilization and Participation in Politics . The M - 19 eventually gave up its weapons , received pardons and became a political party in the late 1980s , the M - 19 Democratic Alliance ( " Alianza Democrática M - 19 " , or ( AD / M - 19 ) ) , which renounced the armed struggle . Eventually the M - 19 returned Bolívar ' s sword as a symbol of its demobilization and desire to change society through its participation in legal politics . In 1990 , one of its more prominent figures , presidential candidate and former guerrilla commander Carlos Pizarro Leongómez , while aboard an airline flight , was murdered by assassins , supposedly on the orders of drug cartel and paramilitary leaders ( disappeared AUC commander Carlos Castaño publicly admitted his own responsibility for the murder in a 2002 book and interviews ) . Some of its other members were also subject to multiple threats or likewise murdered . Antonio Navarro Wolff replaced the deceased Pizarro as candidate and leader of the party , finishing third in that year ' s presidential race . Despite the continuation of smaller scale violence against it , the AD / M - 19 survived through the 1990s , achieved favorable electoral results on a local level and actively participated as a high profile political force in the forging of Colombia ' s modern 1991 constitution , which replaced a conservative document ostensibly dating from 1886 . Antonio Navarro was one of the three co - presidents of the Constituent Assembly of Colombia , together with representatives from the Colombian Liberal Party and the Colombian Conservative Party . Several analysts consider that the AD / M - 19 reached its peak at this point in time and , while never disappearing completely from the political background , it began to gradually decline as a party by its own although many of its ex - members have reached a first line influence in the Independent Democratic Pole coalition .