Police announced a breakthrough Tuesday in the killings of four Muslim men in Albuquerque, New Mexico, charging a man from Afghanistan—himself a Muslim—with two of the slayings and identifying him as a prime suspect in the other killings.

Muhammad Syed, 51, of Albuquerque, was arrested Monday after a traffic stop more than 100 miles from his Albuquerque home. The Afghan immigrant denied any connection to the crimes.

In court documents, in fact, he told police that he was so unnerved by the slayings that he was driving to Houston to find a new home for his family.

But investigators say they have ample evidence to prove his guilt, though they have yet to uncover the motive. The first ambush-style shooting happened in November and was followed by three more between July 26 and Aug. 5.

According to the criminal complaint, police determined that bullet casings found in Syed’s vehicle matched the caliber of the weapons believed to have been used in two of the killings and that casings found at the crime scenes were linked to guns found at Syed’s home and in his vehicle.