By Jeremy Clarke and Duncan Miriri

NAIROBI, Oct 26 (Reuters) - A wave of alleged executions by Kenyan police is terrifying anyone with links to those killed, while families of the missing fear their corpses could turn up next.

Kenyan police came under fire this week from local rights groups who say they executed scores of suspected members of the dreaded Mungiki criminal gang and dumped their bodies outside Nairobi after a morgue in the capital was filled to capacity.

Police deny any wrongdoing in their fight against the group blamed for a spate of beheadings across the centre of the east African country earlier this year.

But relatives of the victims -- who were identified mostly from bloodied scraps of clothing and shards of hyena-chewed bone -- say they are so petrified they can't properly mourn the dead.

"No one will come to my brother's funeral," 28-year-old Margaret Waithera, who was visiting the city morgue to collect her older sibling's remains, told Reuters.

"Everyone is scared the police will think they are Mungiki and kill them."

Standing in the pouring rain with her father, she said she learned of brother's fate only by watching television.

"He went missing, then we saw his clothes on the nightly news where they were ripped up in Ngong Forest," she said. Her brother had been shot twice: in the eye and in the forehead.

She denied he had any links to the Mungiki gang.

"IDI AMIN REGIME?"

Mungiki, which means "multitude" in the language of central Kenya's Kikuyu tribe, emerged in the 1990s as a quasi-religious sect. But it has fast grown into the nations' biggest criminal operation, running protection rackets worth millions of dollars.

It reared its head again ahead of Dec. 27 elections, raising fears of bloodshed before the polls. Analysts say some politicians have had close links to the secretive Mungiki in the past, for instance using gang members as muscle-for-hire.

Police were accused of -- and denied -- extrajudicial killings during two anti-Mungiki raids in Nairobi's Mathare slum in June that killed more than 30 people.

Since then, however, locals say dozens of corpses have been discovered in rural areas outside towns across central Kenya.

Witnesses say most seem to have been shot in the head.

The grim news has kept many Kenyans glued to their television sets in recent days -- and none more than the parents of young men who vanished at the time of the police crackdown.

The family of Daniel Nderitu, 28, now fear the worst.

"How can he have disappeared without a trace after being arrested?" asked Nderitu's brother James, adding that Daniel was taken by a member of a dedicated anti-Mungiki police squad.

"Is this an Idi Amin-style regime?"

AlertNet news is provided by