The Spanish officer who led his armed followers into the Spanish congress in a failed military coup in 1981 has died on the same day that the socialist-led government declassified documents relating to the murky attempt to overthrow the country’s post-Franco democracy.

Antonio Tejero, who was 93, was part of a network of rightwing police and military officers whose efforts to seize power were thwarted after King Juan Carlos refused to support the coup and ordered the generals to obey the democratic constitutional order.

Photographs of Tejero wearing the tricorn patent leather hat of the Guardia Civil and brandishing a pistol at MPs on 23 February 1981 are among the most indelible images of Spain’s young democracy. Tejero, who had been involved in another attempted putsch in 1978, was sentenced to 30 years in jail for his role in the events of 1981, but was released after serving half that time.

Tejero’s family announced his death in a statement on Wednesday, just hours after the government had uploaded 153 documents relating to the coup on its website.

The statement said Tejero had devoted his life “to God, Spain and his family”. His lawyer, Luís Felipe Utrera Molina, also paid tribute to him in a message posted on X.

“Lieutenant Colonel Don Antonio Tejero Molina has died,” he wrote. “A man of honour, of unshakeable faith and with a great love for Spain. May God grant him the peace that men have denied him.”

The former officer remained emphatically unrepentant about his part in the failed putsch. “It cost me my career and my freedom, but despite that I don’t regret having tried,” he told an interviewer five years ago.

Tejero was also one of the people who turned out to protest against the government’s decision to exhume Franco’s remains from the mausoleum in the Valley of the Fallen and transfer them to a suburban cemetery on the outskirts of Madrid in 2019. At the request of the Franco family, one of Tejero’s sons, the priest Ramón Tejero, said mass at the reburial.

The Spanish government said it had decided to declassify and publish dozens of documents about the coup so that people could read them and find out more about what happened in 1981.

“Truth, memory and democracy,” the prime minister, Pedro Sánchez, wrote in a post on X on Wednesday morning. “Because remembering the past is the best way to move forward with progress, harmony and freedom.”

Among the declassified files was a report from the ministry of defence that revealed that members of the intelligence service were involved in, or had knowledge of, the coup plot.

According to the document, there were “six people who either knew the facts before 23 February, or who drew up operational support and then tried to cover their involvement using an operation that sought to justify their movements that day”.

In another document, one of the plotters lamented that the coup had failed because they had left Juan Carlos free and had “treated him as if he were a gentleman” when he was, in fact, “an objective to be removed”.

Juan Carlos was lauded at home and abroad for using a TV address on the night of the coup to face down its leaders and defend Spain’s newly restored democracy.

But there have long been questions about the precise aims of the coup – and about its backers and instigators.

According to an interior ministry file released on Wednesday, an investigation had established that some of the plotters had subsequently attempted to “lessen their criminal responsibility” by trying to implicate the king himself in the plot.

“Defence lawyers for those who really were involved – as well as political groups and political circles sympathetic to their cause – have pushed the alleged involvement of his majesty the king as the main reason for the coup attempt,” the report said.

“In order to do so, they have twisted true facts, maliciously interpreted others, and come up with things that have existed only in the minds of those who thought them up.”