By Martin Murphy BBC Latin America analyst

Violence has cast a long shadow over Guatemala's presidential, parliamentary and local elections being held this Sunday.

Otto Perez Molina wants to expand the police force

The two leading presidential candidates, Alvaro Colom, from the National Unity of Hope Party (UNE) and Otto Perez Molina, from the Patriotic Party (PP), have both pledged to crack down on crime after one of the bloodiest election campaigns in the country's history.

More than 50 candidates, party activists and their relatives have been murdered since September last year, according to the Inter-American Commission on Human Rights.

Guatemala has one of the highest murder rates in Latin America, with some 5,885 people dying by violence in 2006, according to official police figures.

The country's present violence follows a recent bloody past that saw leftist rebels and successive military governments wage a civil war from 1960 to 1996 in which some 250,000 people died or disappeared.

The worst years were from 1960 until 1986, the year democracy returned to Guatemala. It took another decade to sign a peace agreement.

An official inquiry concluded that 90% of the crimes committed during the civil war were carried out by the security forces. Yet very few people have been prosecuted for these crimes.

General Efrain Rios Montt, who governed the country during the civil war's bloodiest years, has never been tried.

Drugs gangs

GUATEMALA ELECTION FACTS 14 presidential candidates Voting mandatory 5.9m registered voters out of pop of 14.6m Run-off on 4 Nov if no-one wins more than 50%

The current election violence has been blamed on a combination of attacks on politicians and activists by shadowy armed groups, reminiscent of the civil war, and attempts by organised crime, drug and youth gangs known as maras to intimidate politicians.

Like other countries in Central America and the Caribbean, Guatemala has become a major transit route for the drugs trade into the US.

Drugs traffickers are also believed to have financed some of the campaigns.

The latest polls suggest no candidate will win more than 50% of the vote, in which case the top two will face a run-off election on 4 November.

Alvaro Colom is a centre-left businessman who, although he was never part of any guerrilla organisation, has said he sympathised with the rebels during the civil war.

Running for the presidency for the third time in a row, he has promised to overhaul the security forces and the judicial system, which many criticise for being slow, corrupt and ineffective.

His main rival, former general Otto Perez Molina, who was previously the head of army intelligence, promises to increase the size of the police force by 50% and revive the use of capital punishment.

Mr Colom says Guatemala would return to a military dictatorship under Mr Perez Molina's rule, an accusation the former general denies, saying he helped to negotiate the 1996 peace agreements.

Alvaro Colom is seeking an overhaul of the security forces

Other candidates, who include the Nobel Peace Prize winner and indigenous activist Rigoberta Menchu and Alejandro Giammattei from the Grand National Alliance (Gana) of President Oscar Berger, have few chances of making it to the second round.

The fact that Mr Giammattei, the government-sponsored candidate, is trailing the front-runners by a long way is perhaps indicative of what Guatemalans think of Mr Berger's four years as president.

Other election issues:

• Poverty and unemployment
• Situation of Guatemalans living in the US
• Free trade agreement between Central American countries, the Dominican Republic and the US