Who killed Antonio?

She grew up surrounded by sophisticated expatriates and socialites. When she married Trzebinski, the son of a Polish aristocrat and a British writer whose work was used in another hit movie, Out of Africa, it seemed two extraordinary people had found their soulmate.

Anna certainly believed that. Soon after Trzebinski's death she revealed that when they met at a lunch, she had to get up and leave because she was overwhelmed by her feelings: "I went home and I was physically sick because I knew I had met the man of my life," she said.

She was married to someone else at that time, but they quickly began an affair. On New Year's Eve, 1989, Anna joined a gathering of friends on the island of Funzi, off the east African coast. Tonio, as Trzebinski was known, crossed to the island in a native canoe. As Anna's husband lay in bed, recovering from a poisonous centipede bite, she recalled, she and Trzebinski made love in the bushes. In a matter of days, they were living together, apparently inseparable.

Anna was divorced and she married Trzebinski during a holiday in California in 1991 and returned to live in a magnificent house, built by Trzebinski himself, in the affluent Langata suburb of Nairobi. They had two children, now aged 11 and 10, and they lived what appeared to be an enviable life. Anna said of that time: "We were this incredible couple with the world at our feet. We just wanted to go out there and party for as much as we could party and live life. Everything was so sublime, so sublime."

Their home became a crossroads for artists and writers, there were constant parties and lunches - a visit to the Trzebinskis was a necessary stop on anyone's East African itinerary. Their home bordered a national park that is a habitat for some of the rarest creatures in Africa.

With his shoulder-length, wavy blond hair, imposing physique and dynamism, Trzebinski was an exotic creature in his own right. He would paint in his studio near the house most days. Stripped to the waist, with classical music booming from powerful loudspeakers, he attacked his canvasses with Herculean energy. At the time of his death he had had a successful show in London and his work had gained a following in Europe and the US. Anna was running his business affairs and to outsiders it seemed their life - and marriage - was perfect. But it wasn't.

ANTONIO Trzebinski had become cap t ivated by Natasha Illum Berg. This young Danish woman lived a short drive from their house and had created something of a stir among the Nairobi expatriates. With her exceptional beauty and enthusiasm for Africa, its wildlife and people, she was highly sought-after, but quickly earned a reputation for being rather cool - indeed, her nickname was The Ice Queen.

The timing of her revelations about her intimacy with Trzebinski, who was 41 when he died, may prove significant. After more than two years, the police investigation into his death has all but ended. Although the Nairobi police say the file is still "active", nothing is being done and there is considerable frustration among the artist's family and friends over the fact that no one has been found guilty of his murder.

It is a perplexing case, riddled with elements that recall the Lord Erroll business. Joss Erroll, like Trzebinski, was a star in his social circle of moneyed Europeans living in Kenya during the last war. Erroll was notoriously priapic and preyed on other men's wives, among them Diana, the wife of Sir Jock Delves Broughton.

In 1941, Erroll was found shot dead in his Buick. Delves Broughton was arrested, tried for murder, but acquitted, although many believed he was guilty and when he returned to Britain he found himself ostracised. He committed suicide in a room at the Adelphi Hotel in Liverpool in December 1942.

Erroll, it was thought, had been murdered because he had enraged a jealous husband.

Tonio's relationship with Illum Berg was no secret - even his wife knew. Indeed, she found out in a shocking way. During the summer of 2001, she said, she had found him distant and she suspected he was seeing someone else. One afternoon, he left his studio on his motorcycle and, although he left the studio locked, she used a gardener's ladder to climb through an open window.

She recalled: "I picked up his phone, hit the redial button and who do you think

answered? I said 'Hello'. She said 'Hello'. I said 'Who is this?' And in her usual arrogant way she said, 'Who am I talking to?' And I recognised her voice. She must have looked at the phone, seen it was Tonio's number and my voice, put the phone down and turned off her mobile. Within 10 minutes, Tonio was back."

The episode led to a screaming row and an apocalyptic, violent outburst. Anna took a craft knife and slashed the paintings in the studio. "I just wanted him to feel my pain," she said later.

Trzebinski left the house and they never spoke again. By email, they agreed to a trial separation and Anna left Africa for America. Trzebinski continued to see Illum Berg. She had been in a relationship, but, as her book makes very clear, her passion for Trzebinski was all-consuming. He was on his way to her house the night he died.

He was found lying a short distance from his Alfa Romeo, so close to Illum Berg's house that her servants heard the shot. The bullet entered under his right armpit, penetrating a lung and his heart. It was fired from a 9mm weapon and it was a wound no one could have survived.

Earlier that evening, he had spoken to his mother, Errol, who lives in Mombasa on the Kenyan coast. She told me: "He had moved back into the house when Anna went to America and he told me he was going out and might be back a bit late. We arranged to talk later.

"It seems he put the children to bed before leaving for Natasha's house, then rang her on his mobile to say he was on his way. He never got there."

Errol Trzebinski relates the events of that night in a calm voice, but she says the fact that no one has been found guilty of her son's murder leaves her in an emotional limbo, unable to move on from her grief. She is planning to appeal to Sir John Stevens, the Metropolitan Police commissioner, to see if Scotland Yard can help.

"It would need an invitation from the Kenyan police," she says, "but I believe that with all the expertise and resources they have, Scotland Yard could progress the case."

She dismisses the theory that her son was the victim of a robbery. "The car wasn't taken; his wallet was still stuffed with money; he was still wearing his wristwatch."

Curiously, the killer seems to have been interested in Trzebinski's mobile phone. The SIM card was removed and later found in the possession of a garage mechanic who said he had found it. He and two other men were arrested for the murder, but later released.

The SIM card, Errol Trzebinski believes, could still yield clues if it were subjected to a sophisticated forensic examination.

She believes her son was murdered by a contract killer. But who would hire a killer to dispose of Trzebinski? And, perhaps more importantly, why? Despite a rigorous scrutiny of his business and private affairs, no answer to these questions has emerged.

But now that the woman he adored, Natasha Illum Berg, has ended her silence, that may change.

Errol Trzebinski hopes so. The only person who wants the affair to be forgotten, she said, is the one who ordered her son's murder.