By Wendy Anders

Police found enough clues to arrest a man suspected of stabbing five students to death in mid-January in their apartment on a quiet residential street in Liberia, capital of Costa Rica’s northern Guanacaste province, said Wálter Espinoza, director of the judicial investigative police agency (OIJ).

A careful review of evidence in and around the crime scene led police to investigate a neighbor of the students, a man by the last names Ríos Mairena. Police are fairly confident the murder was committed by a sole perpetrator.

Using a blood-tracking dog, police said they were able to hone in on Rios’ home located a couple of doors down from the students’ apartment. They thoroughly searched Rios’ home for evidence and collected important clues, said police, who are still in the midst of the complex investigation.

Espinoza said the police’s specially trained blood-tracking dog is the only one in use by police in Latin America, and is an extremely valuable tool in solving tough crimes such as this one.

Rios’ has a history of drug use and a police record. Reports in AMPrensa, a Spanish daily digital media, said Rios’ was out on bail and prohibited from using drugs after a recent arrest.

Police suspect Rios’ entered the apartment under the effect of drugs, instructed the students to bind each other, and then proceeded to kill them, said Espinoza.

In addition, police say that there may have been an underlying sexual motive for the crime, with Rios’ apparently driven by a sexual fantasy with one of the students he killed. OIJ officials found no evidence at the crime scene that the victims had suffered any sexual assault by their killer.