-LRB- CNN -RRB- -- A lawyer who left a videotape saying Guatemalan President Alvaro Colom would be responsible if anything happened to him masterminded his own death last year , a special United Nations commission said Tuesday after an eight-month investigation . Colom had nothing to do with the killing , said Carlos Castresana , head of the International Commission Against Impunity in Guatemala . `` Rodrigo Rosenberg , for some reason , decided to put an end to his life , '' Castresana said at a televised news conference . Rosenberg was shot from behind in a brazen daylight attack while riding his bicycle in Guatemala City , the nation 's capital . He was shot three times in the head , once in the neck and once in the back , Castresana said . Prominent Guatemalan brothers Francisco Jose Valdez Paiz and Jose Estuardo Valdez Paiz hired hit men at the behest of Rosenberg , who told them he was being threatened by someone , Castresana said . The two brothers , who own a pharmaceutical company , had been cousins of Rosenberg through a previous marriage and did not know that he was the target of the assassination , Castresana said . Rosenberg fed information to the hit squad leader that led to his own death , giving descriptions of what the target looked like and where he would be . `` It was the two brothers and no one else , '' Castresana said . `` Not a politician . Not a -LSB- government -RSB- minister . Not a police chief . No one . Just these two brothers . '' About 300 investigators from 11 nations reached their conclusion after an exhaustive examination of 100,000 telephone calls , 9,500 documents , surveillance videotapes , and 135 interviews with 11 suspects and others , Castresana said . Colom had maintained since the May 10 slaying that he was innocent despite Rosenberg 's explosive videotape , which was made public the day after his death . Guatemalan authorities have arrested 11 men on suspicion that they carried out the killing , but the Valdez Paiz brothers remain at large . Their lawyer , Alexis Calderon , denied last week that his clients were involved . `` This is a story being made up to implicate people who did n't have anything to do with it , '' Calderon said . He also said that he did not know where the brothers were but that they would surrender after Tuesday 's conference . Calderon did not answer calls seeking comment Tuesday . Arrest warrants for the brothers were issued December 10 , Castresana said , noting that the suspects were already out of the country by then . Rosenberg recorded the tape blaming Colom three days before his death . He said Colom wanted him dead because the lawyer had been blaming the president and some of his top associates for the slaying of a prominent businessman and his daughter the previous month . Businessman Khalid Musa and his daughter , Marjorie , were killed , Rosenberg said , because they had refused to participate in acts of corruption as the president wanted . Rosenberg was Musa 's attorney . Castresana indicated Rosenberg staged his own killing to get back at Colom and high-level members of his government , whom he could not prove were responsible for the Musa killings . `` He wanted to open a box of lightning and thunder , '' said Castresana , a Spanish judge . Castresana pointed to several indicators of Rosenberg 's state of mind : His mother had died ; he was going through a second divorce , and his wife had taken their young children to Mexico ; he was bereft at the slaying of Marjorie Musa , with whom he had a close relationship ; and he felt a sense of powerlessness because he could not prosecute the people he believed were responsible for the Musa slayings . May 10 , the date of his killing , was Mother 's Day . In two April 21 e-mails , seven days after the Musa killings , Rosenberg wrote , `` I ca n't stop crying '' and `` I feel like I 'm disintegrating , '' Castresana said . Rosenberg made out his last will and testament on April 24 and started going public with his accusations against Colom regarding the Musa slayings on May 3 . On May 4 , he called a meeting at his law office and said he would be leaving the firm , in which he was a partner . The next day , Castresana said , Rosenberg asked a friend to buy two cell phones anonymously . Those cell phones , the lead investigator said , were crucial to cracking the case . Rosenberg used one of the phones to call threats to his personal cell phone and had the other delivered to the Valdez Paiz brothers , who gave it to the hit squad leader . Rosenberg then used the new cell phone he kept to give instructions to the hit squad leader through the second phone , Castresana said . Castresana detailed how the slaying apparently was meant to be paid through a $ 40,000 check . According to the investigator , Rosenberg told his secretary before his death that she would be receiving a check from Panama that should be delivered to the Valdez Paiz brothers . The check had been made out by Luis Alejos , a Rosenberg friend and business associate who at the time was Guatemala 's minister of communication , Castresana said . Alejos resigned from office in June , a few weeks after the slaying . After receiving the check , Francisco Jose Valdez Paiz destroyed it , Castresana said . The businessman paid the 300,000 quetzales -LRB- $ 35,900 -RRB- for the assassination out of his own pocket , Castresana said . The investigator said Rosenberg sent Alejos the money to pay for the killing . Alejos is the brother of Roberto Alejos , the president of the Guatemalan Congress , and a cousin of Gustavo Alejos , who is President Colom 's private secretary . In his videotape , Rosenberg said Gustavo Alejos would be among those responsible for the lawyer 's death if it happened . `` If you are reading this message , it means that I , Rodrigo Rosenberg Marzano , was murdered by the president 's private secretary , Gustavo Alejos , and his associate Gregorio Valdez , with the approval of Mr. Alvaro Colom and -LSB- first lady -RSB- Sandra de Colom , '' Rosenberg said . After the tape surfaced , Colom went on national TV with a vehement denial that he or anyone mentioned in the video was involved . He expressed his sense of vindication in a televised speech Tuesday afternoon . `` I do n't have any rancor in my heart , '' Colom said . `` Just immense gratitude for those who waited patiently with us . '' The United Nations established the International Commission Against Impunity in Guatemala in 2006 to investigate corruption and political violence . More than 200,000 people have been killed in the nation since 1970 , mostly as a result of organized crime , drug-trade violence and a 36-year civil war that ended in 1996 . There were 6,451 slayings in Guatemala last year , of which only 230 verdicts were achieved , Castresana said . That means , he said , that more than 96 percent of the killings in 2009 were not solved .