U.K. authorities took Kimberlee Singler, 35, into custody without incident, Colorado Springs police said late Sunday. Details, including the location of the apprehension, were pending, the police department said.
"Detectives with the Colorado Springs Police Department’s homicide unit continue to work closely with multiple law enforcement agencies in pursuing the ongoing investigation," it said.
In a statement Monday, Britain's National Crime Agency said it arrested a 35-year-old woman in connection with crimes committed in the United States, including two counts of murder and one count of attempted murder.
The agency did not identify the suspect by name but said she was remanded into custody Monday after appearing in Westminster Magistrates Court to begin extradition proceedings.
The Associated Press reported earlier that Singler made an initial appearance at the London court.
Singler was named in an arrest warrant that alleges she committed murder, attempted murder, child abuse and assault, according to police. She was last seen Dec. 23, Colorado Springs police said.
On Dec. 19, officers responding to an early morning 911 call about a burglary at Singler's condo unit found a girl, 9, and a boy, 7, dead at the scene, police said.
Singler and an 11-year-old daughter were hospitalized, they said.
Investigators came to believe that the claim of burglary was unfounded, and the arrest warrant was obtained, police said.
The suspect and her estranged husband have been locked in a contentious, yearslong divorce case, according to court records.
The National Crime Agency said Singler has another appearance scheduled in the same London court on Jan. 29.