The United States has announced a reward of up to $10 million for information leading to the arrest of the alleged leader of the 2019 attack on Nairobi’s Dusit D2 hotel complex. The attack in the Kenyan capital killed 21 people, including a U.S. citizen, and injured 30 others.

Kennedy Macharia was working at the complex on January 2019 when he heard gunshots. He and some of his colleagues barricaded themselves inside their office until police found them and led them out.

However, two of his colleagues were shot and killed. 

Macharia welcomed Thursday’s U.S. announcement of a $10 million reward for information leading to the arrest of Mohamoud Abdi Aden, the alleged mastermind of the attack.

“I think the idea of looking for whoever masterminded the whole thing would be of great help, to serve justice to the families that lost their loved ones, some friends, some colleagues, some workmates,” Macharia said. “I feel it will serve justice and maybe it will bring closure to the whole ordeal.”

Mohamoud Abdi Aden is leader of the Somalia-based militant group al-Shabab. The U.S. State Department officially designated him as a terrorist in October.

U.S. Ambassador to Kenya Meg Whitman announced the reward offer, which is equivalent to more than 1.2 billion Kenya shillings. She said the U.S. is seeking information leading to Aden’s arrest and conviction in any country, plus information on anyone else involved in the Dusit D2 attack. 

“We encourage anyone with information on those responsible for the attack to contact Rewards for Justice on Signal, Telegram or Whatsapp via Kenyan and Somali tip lines displayed on the posters,” Whitman said.

The U.S. reward offer is the third of its kind in three months.

In November, the U.S. offered $10 million for information leading to the capture of three al-Shabab leaders — Ahmed Diriye, Muhad Karate and Jehad Mostafa — alleged to be responsible for attacks in both Kenya and Somalia.

On January 5, the U.S. issued a reward offer for information on Maalim Ayman, believed to have planned an attack on Kenya’s Manda Bay Airbase, which is utilized by the U.S. armed forces for counterterrorism training.

Security analysts such as Daniel Omondi say the U.S. rewards are signaling Washington’s proactive efforts to nab terrorists in Kenya.

“Especially after the 1998 bombing of the U.S. embassies, the U.S. must keep on being on the forefront to help, especially with surveillance and enhancing efforts with regards to collection of information, which is very, very key in preventing further attacks in the region,” Omondi  said.

Kenya and the U.S. have formed a multi-agency investigation unit to counter terrorism and share information to avert attacks. Authorities from both countries say the unit has been a success.