The two gunmen flanked the modest, family-sized Toyota at a busy intersection. Aiming at the driver, they fired a barrage of bullets, nine of which fatally hit Mia Mascariñas-Green in her head and neck.

In the back seat, her 10-year-old daughter and 23-month-old twins watched. Their nanny – who was sitting in the third row – jumped over the divide to shield the children with her body. One of the attacker’s guns jammed and they fled on motorbikes.

Stuart Green, a marine biologist from Hertfordshire in the UK, relates the last moments of his wife’s life with a mixture of anger and extraordinary grief.

“It was 28 bullets shot at an unarmed mother driving her kids home,” he tells the Guardian.

“I don’t really believe in miracles. But you have two shooters on the opposite side of the car, basically shooting towards each other with my wife in the middle. Our three kids are half a metre behind and not one bullet grazed them.”

Green, who moved to the Philippines in the early 90s and fell in love with Mia shortly after, described her as his best friend and hero. The twins “keep waking up at night and calling for mummy,” he says.

Making clear efforts to remain composed, his voice finally breaks while talking about writing her eulogy. “She deserved the best sending off I could give her. That was my focus,” he said. “It was a beautiful union and she was quite an amazing lady.”

Since the attack on 15 February, Green has packed up his house on the island province of Bohol where he lived with his wife, whose work as a lawyer focused on environmental, women’s and children’s issues.

He flew to the capital Manila and will now proceed with a case against the person he says orchestrated the hit on his wife — the defendant in a property dispute Mia had been working on, according to an affidavit Green filed with the local prosecutions office.

The Philippines is one of the most dangerous places in the world to be a lawyer, with dozens killed during the past decade in often-brazen attacks. Two years ago, a judge was shot dead in front of his courthouse.

Lawyers and activists working for environmental causes are particularly at risk. A report by UK-based watchdog Global Witness declared the Philippines as the second most deadly country for environmental activists in 2015, with 33 killings.

Although Mia, 49, worked on several high-profile environment cases, her husband says in the affidavit the one that led to her death was an apparently benign familial dispute over the ownership of a hotel.

Last year, Mia took on a client named Conrada Blomqvist, who said her son-in-law had taken over a 38-room beach resort she owned on the island of Panglao, a popular retreat with tourists.

The man, a 34-year-old named Lloyd Gonzaga, and another person named Romarico Benegi-an were later arrested in October when drugs and guns were found at the property but they were allowed out on bail.

“I started to put two and two together but Mia said everything was fine. I now regret not forcing the issue,” Green said.

“We thought we were good at security ... we thought because she’s local, she knows everyone, everyone knows her, she felt a bit immune to it. We have a very secure house, we have dogs, we follow basic protocols. It just wasn’t enough.”

Since Mia’s murder, police have named both Gongaza and Benegi-an as suspects who are on the run. The chief superintendent of the region was quoted in local press as saying Gonzaga was the “mastermind”.

Green moved to the Philippines as a volunteer. He stayed to champion the rights of local fishing communities and met Mia at a environmental legal conference in Bohol.

For two years, he says he tried to find fishermen with legal problems so he would have an excuse to set up meetings with her.

“She believed there was legal process in place and if you were good enough, you could always win over bad.”

For the young twins, who turn two years old on March 19, the family would hold monthly birthdays. “Mummy would always celebrate with them,” Green said. After Mia died, he said, they kept the coffin in the living room as part of the traditional Filipino wake so the children “could play by their mother for a few more days and get used to the idea that she was asleep.”

Mia had been targeted for her work before, with four failed attempts by defendants and other lawyers at having her disbarred. Green says Mia even received death threats but she said it was just part of the job of being a lawyer.

“The crazy thing is, we were just in the UK for Christmas and we’d actually agreed that I was going to focus much more on the travels abroad and providing the revenues” while Mia would “scale back on the work and bring up” the children.

Now, in pursing justice for his wife, Green knows he is taking a risk. When he filed the case, based on eyewitness accounts of the crime, he said someone came two days later and photocopied all the files he had submitted.

“Of course, it’s a public document, we appreciate that. But someone who no one had ever heard of, isn’t a lawyer, is not from Bohol, came in, showed an ID, Xeroxed everything and left. They know every move that we make. We know who these people are but we don’t know who else is with them.”

The Philippines has been criticised by rights groups for a culture of impunity, especially related to the killings of rights activists, journalists and lawyers. Even apparently straightforward cases can take years to reach court.

Green is determined. Speaking at her funeral, he referred to Mia’s ardent belief that “ultimately the legal system would work”. But he also mentioned the black van that was seen trailing her car the day she died and its registration number, knowing the funeral was attended by hundreds of influential people on Bohol.

The family have received a huge amount of support in the Philippines and abroad. A fund has been set up to try to raise half a million US dollars for the children’s education.

“Mia was very strong that the kids deserved a good education and I’m now in a situation where I can’t totally guarantee that,” he said.

“I’ve had an amazing 21 years in the Philippines where I’ve lived in

fishing villages and seen the beautiful side of the country. And this is the

first time I’ve been introduced to the other side of the contrast here. And

it has really changed my perspective.”