( CNN ) -- Three human heads and three decapitated bodies with notes aimed at high government officials were found Thursday in different parts of Guatemala 's capital , national police said . The notes were addressed to Interior Minister Carlos Menocal and Eddy Morales , the nation 's director of prisons . One of the notes said the officials must impose order in the nation 's prisons or these atrocities would continue , police said . The other said that impunity against lawlessness must end , according to police . The heads were inside plastic bags , one of them in front of the main doors to the national Congress in Guatemala City , police said . `` That 's obviously a first for Guatemala , '' said Samuel Logan , an expert on Latin American gangs and founding editor of the Southern Pulse intelligence report . `` That 's something we 've seen the Zetas ( drug cartel ) do in Mexico . '' Donald Gonzalez , a spokesman for the national police , attributed the slayings to the Zetas or another narcotrafficking group , the Prensa Libre newspaper reported . Gonzalez did not immediately return a phone call seeking comment . Logan did not discount the possibility that anti-crime vigilantes could have been responsible . `` It could also be death squads , '' he said . `` Off-duty police officers or other types hired by local businessmen who say , 'Go after the street gangs . ' `` There 's a lot of moving parts to this story , '' said Logan , who recently wrote a book on the Mara Salvatrucha gang of Central America and is working on a book about the Zetas , which has emerged as Mexico 's most ruthless drug cartel . Logan said in an interview last year that there are two main criminal elements in Guatemala : drug cartels that deal in large-scale exportation and street gangs that sell drugs at the retail level and are involved in other crimes , such as robbery and extortion . In some cases , they work together . When those criminals get arrested , they continue their activities inside prison , said Fernando Carrera Castro , director of the Central American Institute for Fiscal Studies in Guatemala City . `` The prisons , in general , are centers of corruption , '' Carrera said last year . `` From inside prison , they direct kidnappings , extortion , drug trafficking . '' Prison officials are often targeted for violence . In September , three coordinated attacks killed four prison officials in a five-hour span . Left dead were a prison assistant director , a warden and two guards . One guard and a shooting suspect were wounded , as were three citizens . One of the wounded was a woman in the eighth month of pregnancy , news accounts said . At least three prison guards have been killed and five wounded in five attacks this year , published reports say . Logan said that all of Central America is under attack from organized crime cartels , because the region is pinched between Colombia and Mexico , the two biggest sources of drugs in the area . U.S. interdiction efforts that have targeted the flow of drugs through the Caribbean Sea also have forced cartels to travel through the Central American isthmus , Logan said . Within Central America , he said , Guatemala , Honduras and El Salvador have the worst problems . Among those three nations , Guatemala stands out . `` When you talk about a country being hollowed out by organized crime , Guatemala is at the top of the list , '' Logan said . There are two main reasons , he said : geography and an incompetent and corrupt government . `` Guatemala bunches right up against Mexico , '' Logan said . `` Any spillover effect is almost certainly going south . '' Said Heather Berkman , a Central America analyst with the Eurasia Group consulting firm , `` The narcos are coming down from Mexico . '' In addition , Logan said , the federal government is not able to control large segments of the country . For example , Peten state in northern Guatemala , bordered on two sides by Mexico , is lawless , he said . Berkman made the same point in an interview last year . `` The narcos control about 40 percent of the territory down there , which is pretty amazing , '' she said . Berkman also pointed out that the Guatemalan government reduced anti-crime spending in the 2010 budget because of the nation 's dire economic situation . `` If you do n't have resources , you ca n't pay for troops and supplies and intelligence , '' she said . Journalist Alexia Rios Hayashi contributed to this report .
NEW : Beheadings are `` a first for Guatemala , '' analyst says . Notes to top officials found with bodies . Notes said atrocities would continue unless order brought to prisons . Comment: