Police guard the entrance of the touristy hill Villa de San Lorenzo near the area where two French female tourists were shot to death in the northern Argentina province of Salta August 1, 2011. The bodies of the both Frenchwomen, Houria Moumni and Cassandre Bouvier were found last Friday by backpackers in San Lorenzo, west of the provincial capital. [Photo/Agencies]

BUENOS AIRES - Argentine police detained and then released a suspect Monday in the homicides of two young French women who were apparently kidnapped, raped and shot to death while vacationing in a northern province. The crime has prompted both governments to express concern and press for a complete investigation.

The bodies of Moumni Houria, 23, and Cassandre Bouvier, 29, were found Friday alongside a hiking and horseback riding trail in the Quebrado de San Lorenzo, a mountainous and forested park just above the capital of Salta province in northern Argentina.

Police said clues at the scene suggest both were shot to death on July 26, apparently after being raped. The women may have been kidnapped and held for days before they were killed, they added, since they were last seen in their tourist hostel on July 16, where they left their belongings.

Bouvier had a .22-caliber bullet wound in her head. Houria had been shot in the back. Both had clothing pulled down or torn open.

Police detained a suspect whom local news media identified as a man who rents horses for riding on the trail.

The suspect, who was not identified, was questioned by investigative judge Martin Perez and released "for lack of evidence," the justice department announced on its website.

On Sunday, Perez revealed that one of the victims "had hair inside her closed fist, as if she had been fighting with someone."

Provincial security minister Pablo Kosiner said more arrests are possible because multiple people must have committed the crime.

Argentine Foreign Minister Hector Timerman informed his French counterpart, Alain Juppe, Monday about the arrest and said "all Argentina is concerned about this terrible crime."

Salta Gov. Juan Manuel Urtubey, meanwhile, has been meeting with French Ambassador Patrick Flot, who publicly thanked the governor for "keeping in constant contact so that those responsible can be identified."

A still image taken from a video distributed by Salta province police shows the bodies of the two French female tourists, Houria Moumni and Cassandre Bouvier, being loaded in plastic bags after they were found in the touristy hill Villa de San Lorenzo in the northern Argentine province of Salta July 30, 2011. [Photo/Agencies]