In May 2020, Murillo was alleged to be the ringleader in the tear gas case, in which the Ministries of Government and Defense were accused of irregularly purchasing non-lethal weapons at inflated prices.

His refusal to cooperate with various criminal and legislative investigations was denounced by Attorney General José María Cabrera, whom the president dismissed at Murillo's behest.

Cabrera's removal brought the scope of Murillo's influence over the president into question and led to the resignation of multiple ministers amid accusations that he was the "power behind the throne" of the Áñez administration.

Murillo did not pursue university studies, and graduated with a bachelor's degree from the Center for Accelerated Secondary Education before entering the business sector of the hotel industry.

Both posts put Murillo into conflict with the cocalero activist Evo Morales whose political tactics, including roadblocks, seriously interrupted tourism in the Chapare Province.

On 4 January 2010, he secured the support of the Social Democratic Power candidate Ninoska Lazarte, who agreed to withdraw her name from contention in exchange for the position of first municipal councilor.

He returned to the political scene in 2014 when UN, hedging its bets on ex-legislators to confront MAS, presented him as their candidate for first senator for Cochabamba as a member of the Democratic Unity (UD) coalition.

In his statement, he endorsed MDS senator Óscar Ortiz Antelo in his presidential bid and announced that he would not seek reelection, instead hoping to retire to his hotel business in Cochabamba.

He alleged that his "work of more than twenty years" had been reduced to ashes by a mob of cocaleros and militants of the MAS "just because it belonged to [him]"; hours prior, Morales had been forced to resign due to nationwide protests.

Murillo's family —three elderly people, including his sister; and two young girls, one one-year-old and the other six— spent eight days in hiding on the bank of a river in the Villa Tunari tropics before being rescued by a land and air police-military operation.

[16][17] Following Morales' resignation, opposition legislator Jeanine Áñez, a member of the UD alliance, legitimized her succession to the presidency and assumed office as the head of a transitional administration on 12 November.

[25] In December, Murillo made the first visit of a transition official to the United States where he announced that an arrest warrant would be issued against Morales in the "next few hours" on charges of terrorism.

In view of this, the Chamber of Deputies approved on 19 February a formal request demanding that Áñez "instruct the ministers of State to comply with their constitutional duties".

[35] Murillo was implicated in another scandal when on 31 May 2020, the journalist Junior Arias disclosed accusations of irregular purchases of tear gas and other non-lethal equipment at highly inflated prices during the social conflicts of late 2019.

[39] On the same day, Cabrera said that Murillo was attempting to arrange his dismissal with the president due to the investigation he was carrying out as well as his opposition to the privatization of the country's National Electrification Company (ENDE).

[41] AT 11:00 a.m. on 18 September, officials of the Ministry of the Presidency informed Cabrera that he had been dismissed and replaced by Alberto Javier Morales Vargas in accordance with Supreme Decree N° 4345-A.

[52] This time, the MAS argued that such a loophole could not be exploited because, in August, the assembly had passed a law rectifying the ambiguity by specifying the dismissal of a censured minister within twenty-four hours and their prohibition from holding office for a period of three years.

[55] Copa responded by calling the minister's refusal to step down a "clear violation of the Constitution" and decried that "Murillo has a psychological problem because he is very exalted, he is very arrogant, he exacerbates people for no reason".

[62] Nearing the end of Áñez's transitional government, the prosecutor's office accused both Murillo and López of crimes of improper use of influence, negotiations incompatible with the exercise of public functions by individuals, contracts harmful to the State, and breach of duties, with anti-corruption prosecutor Luis Fernando Atanacio Fuentes issuing a formal request for an immigration alert against the pair in order to avoid their preemptive departure from the country.

[65] The whereabouts of Murillo and López remained unclear for some days, leading the prosecutor's office to request a report from the General Directorate of Migration on whether either of the former ministers had fled the country.

[68] The following day, Police Commander Johnny Aguilera reported that Murillo and López departed on a FAB-046 plane from El Trompillo Airport on 5 November, arriving in Santa Cruz, from where they crossed the border through Puerto Suárez and into Brazil.

According to Colonel Pablo García, director of Interpol-Bolivia, López "used his last two days as an authority [to gain a] last favor" from members of the military, who secured the plane for their escape.

[69] As a result of these events, the former head of the General Directorate of Migration, Marcel Rivas, was apprehended on 19 November, with the prosecutor's office accusing him of aiding the flight of the ex-ministers.

[73] The following day, the prosecutor's office announced its intent to indict Murillo and López on charges of breach of duties and improper use of influence, among other crimes relating to the tear gas case, in order to facilitate the activation of a Red Notice from Interpol.

[76] The two Bolivians and three Americans were charged with one count of conspiracy to commit money laundering under allegations that Murillo participated in a bribery scheme related to the tear gas case.

According to the DOJ, the three Florida-based American businessmen paid a total of $602,000 in bribes to Murillo, Méndez, and one other government official in exchange for the $5.6 million contract with the Ministry of Defense for the procurement of tear gas and other non-lethal military equipment.

[78] The following day, Bolivian police raided the Cochabamba properties of Murillo, Méndez, and Paredes, seeking to collect evidence regarding the tear gas case.

[80][81] Soon after Murillo's arrest, former president Áñez, who has been incarcerated in the Miraflores jail since March 2021, denounced her former minister, stating on her Twitter that "corruption is an issue that I never accepted in my government; unfortunately, there were officials who distanced themselves from all ethics.

[86] Before that could happen, the attorney's office requested the postponement of the hearing to 9 August, and on that date, it was delayed again to 8 September due to the "unusual complexity" of the case, and his bail was set at $250,000.

[87][88] After that, Murillo's defense requested a further delay to 8 October before deciding to waive the preliminary hearing entirely and move directly to the prosecution, granting him another month in order to gather evidence for the case.