Vance Boelter is accused of shooting Hortman and husband Mark at their home on June 14 and is also suspected of shooting and injuring senator John Hoffman and his wife Yvettte.
Boelter was apprehended late on Sunday night local time, the Associated Press reports.
The 57-year-old is alleged to have killed former House Speaker Hortman and her husband at her home before fleeing the residence on foot.
Senator Hoffman and his wife, Yvette, were injured at their Champlin home, about 15 kilometres away.
The FBI issued a reward of up to US$50,000 (A$77,000) for information leading to his arrest and conviction.
They circulated a photo taken Saturday of Boelter wearing a tan cowboy hat and asked the public to report sightings.
Authorities allege Boelter wore a police uniform at the time of the shooting.
Boelter reportedly remains in custody after being arrested by authorities.
Boelter was captured in Minnesota, however officials did not immediately confirm where, AP reports.
Drew Evans, superintendent of the Bureau of Criminal Apprehension, said at a news conference a nationwide warrant was out for the suspect’s arrest.
Evans said authorities found a car very early Sunday they believed Boelter was using, a few miles from his home in Green Isle, in the farm country about an hour west of Minneapolis.
He also said they found evidence in the car that was relevant to the investigation, but did not provide details.
–Reporting with Associated Press
