( CNN ) -- Just days after an arson attack left a Bolivian radio personality in critical condition , police arrested four suspects . Now , the victim 's family says , comes the real test : Will investigators uncover the mastermind behind the attack ? The daylight attack on Radio Popular , a small FM station in the southern city of Yacuiba , happened Monday , as owner and host Fernando Vidal was on air conducting an interview . Four men forced their way into the radio station , said Vidal 's son-in-law , Esteban Farfan . Two entered the studio . Listeners heard live on the radio the gunshot of one of the men , and the ensuing scuffle between Vidal and one of the intruders , while the other poured gasoline on him and his equipment . They lit Vidal on fire and fled . Read more : Bolivia weighs regulating social media . The 70-year-old radio personality , a former mayor and councilman , survived , but remains in critical condition with burns to his face and body , Farfan said . Another employee in the room , Karen Arze , suffered burns to a lesser extent and also is hospitalized , he said . Others escaped the radio station through the windows . The assault sparked international condemnation . It was a `` vicious and brazen '' attack , the spokesman for the U.N. High Commissioner for Human Rights said . Three men were arrested the next day as they tried to cross the border into Argentina , just miles from Yacuiba . They were charged preliminarily in connection with the attack , police commander Orlando Gongora said . A fourth suspect was arrested Wednesday and is awaiting a formal preliminary charge , he said . Police worked for 48 hours straight to identify the attackers , Gongora said . But Vidal 's family insists that the incident has deeper roots . Read more : Bolivian officials , mutinous police continue talks . `` ( The police ) have done the easiest thing -- to arrest the four suspected attackers , '' Farfan said . `` Now we need to reveal the masterminds behind this . '' Vidal is an outspoken and respected journalist who made enemies with his opinions , Farfan said . A leftist , Vidal was once close to President Evo Morales , but the journalist broke off his support over what he described as the president 's turn to authoritarianism . He is a relentless critic of corruption , Farfan said . He calls out politicians who allegedly grow their personal bank accounts with state funds and routinely calls for investigations into corruption . At the time of the attack , Vidal was interviewing two guests on the topic of smuggling in the border area , leading to initial speculation that an organized crime group tied to the smuggling was behind the incident . But that explanation seems too convenient to Farfan . He believes that political opponents had a role in the attack against his father-in-law . `` The message is clear , '' Farfan said . `` ( The attackers ) want to shut us up . '' But the cash-strapped station borrowed equipment and was back on the air less than 24 hours after the attack . The police commander is aware of the theories that someone ordered the attack on Vidal , but said it 's too early in the investigation to know for sure . For police , the motive and any affiliation the four suspects may have with organized crime or other interests remains unknown . Before their arrests this week , the suspects had been in trouble with the law before , but only for minor robbery charges , the commander said . That does n't make sense to Farfan . `` The question is : Who would benefit from Fernando Vidal 's commentaries being silenced ? ''
Attackers lit Fernando Fernandez on fire during an interview on his radio show . The year - old is in critical condition . Police have arrested four suspects in the attack . But Vidal 's lawyer says there must be a motive behind the brutal attack .