A week after a Japanese couple were attacked in Guayaquil, one of Ecuador's largest cities, Interior Minister Jose Serrano said Sunday that prime suspects in the case have emerged and indicated they may be arrested within a few days.

According to the Interior Ministry, Tetsuo Hitomi and his wife, Mariko, arrived in western Guayaquil on Dec. 28. The ministry said that after dining at a restaurant located in a different hotel than the one they were staying at, the Hitomis took a passing taxi in the street instead of using the hotel's taxi service, which they thought was too expensive.

The ministry speculates that flagging down a taxi on the street, instead of using a hotel taxi, could have been the reason the couple got into trouble.

While on the way to the hotel where they were staying, Tetsuo was shot three times and robbed of his belongings, the ministry said. Mariko, meanwhile, was shot after the two had been dragged out of the taxi.

Investigative authorities have been focusing on footage from ATM security cameras, as the couple were robbed of about $500 (¥52,000) in cash, their mobile telephones and credit cards.

The two were found lying in a darkened area next to a local school. At around 10:30 p.m., what sounded like a gunshot crackled through the area.

According to witnesses, a group of men was seen in two cars, a yellow taxi and a black car, that sped off to the west soon after the shooting.

The victim, later identified as Tetsuo, was found lying barefoot on the ground with his upper torso exposed. He was not moving.

The woman, believed to be his wife, kept screaming her husband's name while repeatedly tapping and rubbing the man's cheeks.

The wife indicated that the taxi stopped and let the robbers in.