Mr Sánchez was nearing the final leg of his mammoth trek from Madrid to Doha for the Fifa 2022 World Cup. He has not posted since. All contact was lost on 2 October.
After weeks of concern among friends and family over his whereabouts, it emerged that the 41-year-old was in custody in the Iranian capital, Tehran.
The Hengaw Organization for Human Rights, based across the border in Iraqi Kurdistan, sources as saying he had been "kidnapped by Iranian security forces" after visiting the grave of Mahsa Amini
On 2 October, Mr Salamanca spoke to Mr Sánchez on the phone. He had planned to join him on his trip through Iran, but was calling to say he had to pull out.
Mr Salamanca said his friend had been upbeat about the prospect of travelling through Iran, a country he visited in 2019 during a similar trip to Saudi Arabia.
Mr Sánchez, a former paratrooper and passionate Real Madrid fan, was planning to go to Tehran, where a television station wanted to interview him. He was then going to head to Bandar Abbas
He told his friends and family that he would have little internet in Iran, so initially they had not been too worried when he was not contacting them.
Mr Sánchez started his trip in January, travelling across Europe and Turkey, sleeping in a tent, hotels and people's homes, before entering Iraq.
When family and friends were told by the Spanish government that Mr Sánchez was in jail, no official reason was given for his detention. His mother told AP that the family was "filled with hope"