Fresh details have emerged about arrested murder suspect Kevin Kinyanjui Kangethe.
This comes amid a push on authorities to repatriate him directly to the US without him going through court processes.
Police said the man had an Interpol Red Notice on his head.
Massachusetts authorities are hoping to take advantage of Kenya’s extradition treaty with the US, which led to the conviction of two members of the notorious Akasha family on drug trafficking and other charges.
Kangethe was arrested at a club in Westlands on Monday night after being on the run for two months.
He is wanted over the alleged murder of Margaret Mbitu on diverse dates between October 30, 2023, and November 4, 2023, in Boston, USA.
It has emerged the man is a US citizen who had moved to Boston when he was young.
He comes from Thogotho, Kiambu county where his parents lived. His mother died while he was young and had separated from his father, authorities say.
He has three other siblings, two brothers and a sister.
The other brother was deported from the US after serving a sentence, police investigations show.
Another brother is a US citizen currently in the US.
The sister lives in Europe. Police say when Kangethe left the US in November 2023, he moved to an apartment owned by a relative in Nairobi.
The team visited the house for a search as part of the probe into the incident.
In the US, Kangethe is a property owner, officials said.
"He is a rich man in the USA as he has property there," an investigator in the case said.
On Tuesday, the US embassy in Nairobi commended Kenya for helping apprehend Kangethe.
“Embassy Nairobi commends the efforts of Kenyan law enforcement for apprehending Kenyan fugitive Kevin Kangethe, suspected to have murdered Margaret Mbitu in Massachusetts sometime between October 30 and November 4, 2023,” the US Embassy said in a statement.
He was positively identified at the Gigiri police station by US officials.
Kenyan detectives had last November received a request from the US authorities to arrest Kangethe for alleged murder in Massachusetts.
The victim’s mother said she was planning to break up with the suspect.
An arrest warrant was issued on November 2, after Massachusetts State Police found the body of 31-year-old Margaret in a car at Boston’s Logan Airport Central Parking garage the night before.
Detectives had been visiting a home in Thogoto, Kiambu County, believed to be that of the suspect but did not find him.
US Whitman area police said Margaret was last seen leaving work in Halifax around 11 pm on October 30.
At some point after that, investigators said she was murdered.
Margaret’s mother, Rose Mbitu, told the media in the US that her daughter was planning to break up with Kang’ethe.
At 6.30 pm on November 1, police officers in Boston found Margaret’s car with her body inside.
US authorities are convinced of one thing—that Kang'ethe, 40, murdered Magret, as she was affectionately known to family and close friends, before buying tickets for a 16-hour flight to Nairobi, a move detectives believe was to avoid prosecution.
The tickets, it has now emerged, were bought early on October 31 morning, just hours after Margaret’s death.
Preliminary evidence gathered from the deceased’s car indicated that Kang'ethe was the primary suspect.
Margaret lived with her family in Whitman and worked in Boston Area Multi-Services Inc (Bamsi) in Brockton, about 7.2 kilometres away.
On October 30 night, she drove 62 kilometres to Boston Logan Airport to see Kang'ethe.
He lived in Lowell, 80 kilometres from Margaret’s home in Whitman.
Local media reported that surveillance footage placed Margaret’s car in Lowell and Chelsea, Massachusetts, the day before she was killed.
The 31-year-old nurse clocked out of her shift at 11 pm last October 30.
She got into her white Toyota Venza and drove off, in what would be the last time she would be seen alive.
Those close to Margaret knew she would return home after work.
Family members reported her missing after she did not return home and could not be reached by phone.
It is still unknown whether she knew her partner was planning to travel to Kenya.
Two days later, Massachusetts State Police officers found Margaret’s body in her car.
Authorities have not revealed much, except that preliminary evidence points to Kang'ethe as the prime suspect.
Margaret was a naturalised US citizen. She graduated from Quincy College in 2018 and worked for Bamsi, a non-profit organisation.