I was having a nap on the settee when Martin, my son's best friend, rang and said that Steven had had an accident and was dead. The phone then cut out. I must have sat there for over an hour totally shut down. He then rang again and said three men had burst into the house he and Steven shared in the Philippines, held a gun to his head, and then gone into Steven's room next door and shot him dead. It was July 2002. He was 32.
I was shivering, but had this terrible urge to be with my son. My husband Alan - Steven's stepfather - and I arrived in the Philippines two days later. We immediately went to see Martin, the co-director of my son's softwear company. I suspected everybody at that time, including him. They had been in the house they lived in during the week in Makati, the business district of Manila. Steven used to return home at the weekend to his wife and children in Angeles, a three-hour drive away. I couldn't understand how the killers could have got into the house without breaking in, gone into Martin's room, left him, then killed Steven. I was so angry. But after listening to him I realised he had nothing to do with it because he was so traumatised and was constantly looking over his shoulder.
I met up with Steven's wife, Evelyn, who was 23, at the funeral parlour. They had known each other for eight years and had been married for six. We liked her. She was always very polite and we got on so well. It didn't worry him that she had been a dancer in a bar, so it didn't worry me. But when I met her this time she was unusually cold. She just wanted to know if I had seen Martin and what he had said and seen.
She said her family was staying at their home in Angeles and she wouldn't let me go there, which I found suspicious. I went anyway with a bodyguard as well as a police escort. There was no one there apart from Evelyn, the maids and the children. Her landlady told me Evelyn had been entertaining a lot of male friends while Steven had been away during the week.
Evelyn didn't get any more relaxed with us and on one occasion called me saying she wanted to meet me in Angeles city at midnight. When I told one of Steven's friends, he said if we had gone, we would have been dead, too.
I met her the next day and gave her about £200 to feed the children and pay the bills. At the time, Jessica was three and Joshua 13 months. When I phoned her that evening, she was having a party, which she claimed was a wake. The police had also said that she hadn't shed a tear when they collected her to see the body, and all she said was that her husband had a house in England and some insurance money.
Steven had recently told me their relationship was strained; things were going missing, Evelyn wasn't paying the bills, and he had started to cut her allowance. I found among his things a receipt for her wedding ring, which she had pawned just before his murder.
A week after I arrived, I hired a private detective because I wasn't satisfied the police were doing enough. The detective watched her house and took pictures of the people going in and out, and Martin recognised one of the gunmen from them. His name was Arnold Adoray and he turned out to be Evelyn's boyfriend. Martin and I went to the police and, a month after Steven's death, Adoray was arrested, along with one of his accomplices, who Martin also recognised from the pictures. Evelyn claimed she didn't know them.
I had been looking after Jessica for the weekend when we were called by the British Embassy who told us that we should leave the country immediately, as they were worried about our safety. We returned to England at once with Jessica, who had a British passport.
I carried on with the case from home. I had to find Joshua because Evelyn had spirited him off to a remote province. I also had to make sure the two men stayed in jail by finding witnesses and evidence. They were there on the strength of Martin's identification, but he went into hiding after we came back because he was frightened for his life.
We paid a policeman to negotiate with the relatives who had Joshua and he was taken to Manila. One of my informants brought him back to England that November. I couldn't go because Evelyn was saying I had kidnapped her daughter and I would have been arrested.
The third gunman, who was Evelyn's brother-in-law, had also fled. I insisted that my lawyer take out a warrant for his arrest. He wasn't arrested until a year later when one of my informants found out where he was hiding in the jungle, 1,000 miles away.
I had to pay for boats so that my informants could catch him, two policemen to fly there to arrest him, and for everyone to fly back to Manila. Including my lawyer, my informants and the police, I spent £53,000 and had to remortgage the house twice.
Finally the third man made a statement saying Evelyn had given him the house key and he had kept watch while they shot Steven. I had to agree to a plea bargain, which meant he would go free if he helped convict Evelyn and the other two. The men were found guilty and sentenced to 30 years each. And I was there when Evelyn's verdict was announced in November 2004.
She was convicted of murder, which warranted the death sentence, but I said no. It wasn't for moral reasons. How can a person suffer for their crimes when they're dead? She was given 40 years with no remission. I thought: "You've made me wake up every morning without my son and now I'll make you do the same because I've got your son and his sister."
People have praised us for not giving up. But I just did what any mother would do in the circumstances.
Margaret Davis was talking to Julia Stuart. Her book 'For the Love of My Son' is published by Hodder this week, price £6.99Reuse content