José Luis Rodriguez Zapatero is suspected of being unable to show proof he paid import duties on the jewellery.
Corruption probes of colleagues and relatives have put Spain's premier into a fight for survival.
The searches come amid a series of scandals affecting Prime Minister Pedro Sánchez's PSOE.
Begoña Gómez is accused of using her relationship with Pedro Sánchez to advance her private career.
Spain's prime minister delivers a strong rebuttal to US President Donald Trump's threat to end trade with his country.
European nations say they want to work better together but have differing priorities
The release comes on the same day as the death of the coup leader, Antonio Tejero Molina.
Prime Minister Pedro Sanchez says the shelters will be in public buildings across the country.
Álvaro García Ortiz is barred from the post for two years and must pay €10,000 in compensation.
