A top al-Shabab militant, Zakariya Ahmed Ismail Hersi, has givenhimself up, Somali officials say.
Mr Hersi, a leading figure in the militant group's intelligence wing, surrendered to police in the Gedo region, they add.
In June 2012, the US state department offered $3m (£1.9m, 2.5m euros) for information leading to his capture.
It comes three months after al-Shabab leader Ahmed Abdi Godane was killed in a US air strike.
A Somali intelligence officer, quoted by the Associated Press news agency, suggested Mr Hersi may have surrendered because of a dispute with al-Shabab members loyal to the former leader.
Mr Hersi fell out with Godane last year and has been on the run ever since but he is still a powerful figure, says BBC Africa editor Mary Harper.
'No fight' Police stormed a house Mr Hersi had been hiding in for six days, close to the border with Kenya, after receiving a tip off, the district commissioner of the town of El Wag told the BBC.
He said that although Mr Hersi had a pistol, he did not put up a fight.
"Al-Shabab leader Zakariya Ismail surrendered to government forces in El Wag, Gedo region. He is expected to be flown to Mogadishu tomorrow," an unnamed official told Reuters news agency.
There has been no immediate comment from al-Shabab.
Ahmad Umar was named the new leader of al-Shabab, days after Godane's killing last September.
The US has supported the African Union (AU) force that has driven al-Shabab out of the capital Mogadishu and other towns since 2011.
The al-Qaeda-linked fighters want to overthrow the UN-backed Somali government and frequently attack government targets as well as neighbouring countries that provide troops to the AU force.
Three members of the AU force and a civilian contractor were killed in an al-Shabab attack on its headquarters in the capital Mogadishu on Thursday.