He says he has been involved in recovering at least 25 bodies since midway through last year.

When a BBC team visited the area in Siaya county last month, the diver explained how some of the bodies he found had had their limbs tied together, while others were in sacks.

At the time he said some police officers were unhappy that he had spoken to human rights activists and journalists about the situation.

He was asked not to speak to the media - and the police also dispute his timeline, saying bodies have been discovered over two years.

Haki Africa says the man has now been threatened by the police.

The diver was recently summoned by them, detained for eight hours and had his phone confiscated, the human rights group said in a statement

Haki Africa's director Hussein Khalid told the BBC the organisation had decided to take him into hiding because of concerns for his wellbeing.

But Siaya County Commander Michael Muchiri says there is no reason for concern.

The diver had been working well with his officers and the police "would not threaten someone who has been very helpful to us", he said

Of those bodies found by the diver, two have so far been identified following the recent news coverage.

In both cases, the men had been reported missing within the last three months - and had both last been seen alive more 200km (124 miles) away from River Yala, raising questions about how they got there.

Human rights groups have questioned whether there is police involvement in the deaths.

The security forces are usually among the first suspects when suspicious deaths and disappearances occur - given the well-documented cases directly attributed to officers.

But the authorities have asked the public to stop the speculation and wait for the investigations to finish.

Last week, the chief pathologist completed autopsies on 17 of the bodies, but the results are yet to be shared publicly.