Former Guatemalan police chief Marlene Blanco Lapola has been arrested for alleged involvement in extra-judicial killings in 2009.
Ms Blanco and several others are accused of belonging to a group that killed at least three people suspected of extorting money from businessmen.
Her arrest followed an investigation by the UN-backed International Commission Against Impunity in Guatemala (CICIG).
She has denied the accusations, saying she is the victim of "persecution".
Ms Blanco was head of the police and deputy interior minister under former President Alvaro Colom, who left office at the beginning of this year.
It is alleged she and others in the interior ministry ran a campaign of "social cleansing" against criminal suspects.
Former President Colom was himself accused of murder in 2009 but cleared after an investigation by CICIG.
The UN-backed commission was set up by the UN in 2006 to help Guatemala reform its justice system and confront organised criminal gangs that have infiltrated the state.
Corruption, violence and organised crime are rife in Guatemala, and the country has a long history of impunity.
But in recent weeks there have been several successful convictions for killings during the country's long civil war, and the former military ruler Efrain Rios Montt is facing trial for genocide.