The man police said shot and killed Setauket's Ross Reisner will be arraigned on murder and harassment charges on Friday, according to the Suffolk County police.
Brett C. Knight will be arraigned at the First District Court in Central Islip and charged with second-degree murder, a felony.
Police said Knight's last known address was in Midvale, Utah.
U.S. Marshals from Tennessee arrested Knight in that state on Wednesday, after launching a nationwide manhunt for him. Police had believed Knight, after committing the Sept. 24 murder, bought a motorcycle and fled the Setauket area.
The murder of Reisner shocked many in the Three Village community, though early on in the investigation police told the public it was a targeted attack.
Police said Knight shot Reisner, a beloved figure in Long Island's equestrian community, through a window at the man's Upper Sheep Pasture Road home. Reisner took a bullet in the chest and died. Police said his partner, Kevin Murray, was also targeted, but he was only grazed by a bullet.
Police are expected to walk Knight out of the Sixth Precinct Friday to bring him the Central Islip.