Maria Santos Gorrostieta, the Mexican figure who has just suffered a brutal death, was described as a heroine of the 21st century because of her fearless political stand against the drug cartels ravaging her country. It was the third attempt on the life of the 36-year-old medical graduate by those involved in the illegal industry which generates billions of dollars and in recent years has claimed tens of thousands of lives. Gorrostieta, the former mayor of the remote town of Tiquicheo, continued to speak out against the drug gangs, undeterred even by an attack which killed her first husband and left her badly scarred and in constant pain.

On 12 November, as she drove the youngest of her three children to school, she was dragged from her car in an ambush by gunmen who were clearly aware of her regular movements. According to local reports she was assaulted but, begging them to spare her child, eventually went with her abductors. Her family clung to hopes that she was being held for ransom, but a few days later her badly bruised body was found dumped by a roadside. She may have been stabbed and burnt before being killed.

Her death was part of a familiar pattern, since more than a score of mayors have been assassinated on the orders of drug barons in their response to the war on their activities which was declared by President Felipe Calderon six years ago. Senior police officers have also been killed, with a number of female officials among those targeted. Gorrostieta had received official protection but this was withdrawn a year ago. President Calderon's sister Luisa Maria said recently: "All mayors are at risk."

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Gorrostieta's home town of Tiquicheo is in the so-called hotlands of the state of Michoacan, a rural region where drug cartels have a strong presence. During her time in office, from 2008 until 2011, she publicly denounced them.

Born in 1976, she graduated in medicine from university in the city of Morelia. During her political career she joined first the Institutional Revolutionary party and later the left-wing Democratic Revolution party. She never wavered, however, in defining opposition to drug groups as her most important mission.

The first attack on her came in October 2009 when gunmen opened up on a car in which she was travelling with her husband, former mayor Jose Sanchez, killing him and injuring her. Three months later gunmen launched a determined attack with assault rifles, hitting her van with at least 30 bullets. Three of them struck her, leaving her using a colostomy bag and in pain for the rest of her life.

In an act of defiance she released photographs of her dreadful injuries, writing, "I wanted to show you my wounded, mutilated, humiliated body because I'm not ashamed of it – it is living testimony that I am a strong and righteous woman."

Gorrostieta, a devout Catholic, declared: "I have had to bear losses that I would not wish on anyone, and have had to accept them with resignation and with the knowledge that it is our Lord's will, and I have gone on, even with a wounded soul. Despite that, and despite my own safety and that of my family, what occupies my mind is my responsibility towards my people – the children, the women, the elderly and the men who break their souls every day without rest to find a piece of bread for their children."

In words which would inevitably be seen by drug lords as an open challenge to their violent authority, she explained that she found it impossible to surrender because she had to educate her three children by setting an example. She went on: "My long road is not yet finished. I will continue fighting. I will get up however many times God allows me to, to keep on searching, negotiating plans, projects and actions for the benefit of all of society, but in particular for the vulnerable ones. This is who I am."

Her area of Michoacan is the base for several particularly ruthless cartels, who cultivate drug crops and synthesise other substances, mostly for export to the US. The cartels, which are often locked in lethal rivalry, combine a routine use of violence with a penetration of policing and the political and system by a mixture of intimidation and bribery, using their huge reserves of cash. As a result the federal authorities believe that some local mayors and police chiefs are on the take from cartels. Several years ago 10 mayors and other officials were arrested on suspicion of corruption.

After her mayoral term Gorrostieta stood for election to the Mexican legislature. Although she did not win a seat, her decision to stand was seen as confirmation of her determination to remain in public life, even though she admitted she had a daily struggle to erase "the images of the horror I lived."

Her continuing commitment to seeking office meant that she remained high on the assassination list of the cartels. Her outspoken opposition, and her refusal to take drug money, appear to have sealed her fate.

Maria Santos Gorrostieta, politician: born 1976; married firstly Jose Sanchez (died 2009; one daughter, two sons), secondly Nereo Delgado Patinoran; died on or before 17 November 2012.