"As it looks now, he was strangled by his compatriot, but we'll see what the rest of the investigation shows," Tunda Wa Kasende told Aftenposten newspaper.
Joshua French found Moland dead in their shared cell a week ago, bringing a new urgency to diplomatic efforts to negotiate his freedom.
The two had been jailed for four years since being sentenced to death for killing their driver on a visit to the country in 2009.
Wa Kasende blamed Norway for the failure to negotiate a solution when he travelled to the country this May.
"I had expected that we could sit down and discuss how to come to a solution, but it didn't happen," he said. "They just said we had to release the two men, and that was that."
"If someone is convicted of something, do you think that your government would just release them?" Kasende complained. "Do you think we do not have any laws in African countries?"
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French's mother, Kari Hilde French, was on Sunday thrown out of the prison where her son is being held.
"Someone higher up has told the prison not to let in any guests, even me or the lawyer," she told TV 2. "I think it's especially important to be with Joshua now. He looked very tired."