By Edward McAllister
BANJUL, Jan 21 (Reuters) - He vowed to rule Gambia for "a billion years".
But Yahya Jammeh, who ran the nation of 1.8 million for a generation after seizing power in 1994, was forced out by regional military forces this week after refusing to accept his defeat in a Dec. 1 election.
True to his reputation as one of Africa's most unpredictable leaders, Jammeh defied deadlines to leave power but then said on Saturday he was stepping down as West African troops closed in.
Jammeh denies allegations of torture and killing opponents while in power. But his rule and a flagging economy saw thousands flee across the Sahara and Mediterranean to Europe each year.
Hours before Jammeh's announcement, new President Adama Barrow, who was sworn in in neighbouring Senegal last week, dared not believe that his opponent had finally given in.
"We are skeptical because he is so unpredictable," Isatou Touray, a senior Barrow aide, told Reuters.
The concerted way in which West African leaders rounded on Jammeh after his election defeat showed his isolation, which had worsened as his behaviour grew increasingly bizarre.
He claimed to have a herbal cure for AIDS that only worked on Thursdays and advocated slitting the throats of homosexuals. In 2009, he arrested hundreds of people for witchcraft.
CHARM AND TORTURE
In his earlier years, Jammeh showed glimpses of charm and generosity. When celebrating his 48th birthday in Banjul in May 2013 he saw a street hawker selling peanuts with a child strapped to her back. Without hesitating, he sent an aide over with a gift: $1,000 in cash, double the average annual wage.
"He could change a life in minutes," said his former press secretary, Fatou Camara, who witnessed the incident. "When you are close to him, it is impossible to believe the killings."
Over time, such incidents became rarer as paranoia set in and Gambia morphed into a repressive police state. That showed itself as he reversed course over his election defeat.
"I am not a coward. My right cannot be intimidated and violated. This is my position. Nobody can deprive me of that victory except the Almighty Allah," he said on Dec. 21 as the diplomatic offensive against him gathered steam.
When Jammeh deposed the regime of Dawda Jawara, who had ruled since independence from Britain in 1965, he was welcomed as a fresh start, a quiet man with little education who grew tomatoes and lettuce on his farm.
Friends and victims alike say he changed after a coup attempt by a vanguard of the military in 2006.
"He could be very jovial and kind and then lose his temper like a mad dog," said Momodou Sowe, 36, an aide to Jammeh between 2003 to 2012.
Musa Saidykhan, then editor-in-chief of The Independent newspaper, was arrested shortly after the coup. His paper had reported Jammeh understated the number of people rounded up.
Saidykhan was taken to the National Intelligence Agency, next to one of Banjul's white sand beaches.
There, in a room Gambians nicknamed the "Crocodile Hole", agents electrocuted his genitals, beat him with batons, suffocated him with a plastic bag and broke his right hand.
"They said I write with my right hand and that is what is causing the trouble," he told Reuters. Saidykhan left Gambia after his 22-day ordeal and is now a social worker in the United States.
As the economy struggled from lack of investment, Gambians became bolder, expressing dissent even after dozens were arrested for protesting in April and May last year.
"The fear began to erode," said Jeffrey Smith, from campaign group Vanguard Africa. "People had had enough." (Additional reporting by Emma Farge and Ed Cropley; Editing by Matthew Mpoke Bigg, Larry King)