The noose around the criminal pair began to tighten at the end of March when a resident of Bilbao told local police that a higly valuable ring had been stolen from her home.

She said that her search for the missing piece had revealed other jewels were missing from her home too. Several days later, it emerged a similar suite of thefts had taken place at the daughter of the victim. 

Police soon suspected a cleaning woman who worked at the houses of the two woman who had been robbed was responsible for the crimes. They then established that her boyfiend was the fence in the operation.

The pair were then detained in late April.

Further investigations into the pair showed that they had already flogged off most the stolen jewels at the same gold trading shop in Bilbao.

But the criminal masterminds clearly hadn't done their homework properly. One of the items the cleaning lady slipped into her bag — a ring mounted with a diamond — fetched the pair €300 ($390) at the gold trading establishment.

The items's actual value, however, was closer to €200,000 .

The manager of the gold shop had managed to convince them that the stone was of little value.