OSLO — The police arrested one of Norway’s wealthiest people on Tuesday and charged him with killing his wife, the latest twist in a case that has riveted the nation since reports of her kidnapping emerged more than a year ago.

The police, saying they now believe the abduction was fabricated, arrested the husband, Tom Hagen, 70, a energy and real estate multimillionaire, on suspicion of murder or conspiracy to commit murder.

His wife, Anne-Elisabeth Hagen, disappeared from their home in a quiet suburb of Oslo, the Norwegian capital, 18 months ago. Her body has not been found, but investigators have suggested for some time that they believed Ms. Hagen had been killed.

When news of Ms. Hagen’s disappearance first broke in January 2019, the police said that she had been kidnapped and that a hefty ransom, to be paid in cryptocurrency, had been demanded.