Originally Published: 10 AUG 22 02:43 ET

Updated: 10 AUG 22 11:18 ET

By Nouran Salahieh and Christina Maxouris, CNN

(CNN) -- Hundreds of tips poured in after Albuquerque police sounded an alarm about the shooting deaths of four Muslim men in the city, leading to an arrest in the killings on Tuesday.

Though authorities are still searching for a motive and working to confirm whether they're all related, police have arrested Muhammad Syed, 51, of Albuquerque, saying he's being charged in two of the deaths. He also is the "primary suspect" in all of the killings, one of which happened last fall and three of which happened in recent weeks, police said.

"Detectives discovered evidence that shows the offender knew the victims to some extent and an interpersonal conflict may have led to the shootings," police said in a news release Tuesday.

Tips pointed investigators toward Syed, who police believe was in possession of at least two firearms that matched evidence from two of the crime scenes, according to Kyle Hartsock, deputy commander of the city police department's criminal investigations division.

One of the firearms recovered in his home has been linked to bullet casings found at the scenes of two of the killings, while casings from a handgun found in his car were linked to one of the scenes, according to the arrest affidavit.

The killings took place between November and August, with the latest three happening within the span of two weeks.

Police said that the first three victims -- Mohammad Zaher Ahmadi, 62, killed November 7; Aftab Hussein, 41, killed July 26; and Muhammad Afzaal Hussain, 27, killed August 1 -- were "ambushed with no warning, fired on and killed." A fourth man, 25-year-old Naeem Hussain, was shot and killed Friday after attending a funeral for Hussein and Hussain.

A criminal complaint obtained by CNN affiliate KOAT sheds more light on two of the killings.

On July 26, police responded to Rhode Island Street, where they found Aftab Hussein with multiple gunshot wounds, lying next to a car. Detectives learned that the gunman had waited behind a bush near the driveway where the victim usually parked his vehicle and fired through the bush multiple times when Hussein got out of his vehicle, according to the complaint.

On August 1, police got a call about a drive-by shooting near the intersection of Cornell Drive and Garfield Avenue. They found Muhammad Afzaal Hussain with multiple gunshot wounds, the complaint states.

The suspect, Syed, is being charged with the July 26 killing of Aftab Hussein and the August 1 killing of Muhammad Afzaal Hussain, police said.

As for the other two killings, there is evidence "strong enough that" authorities view Syed as the "most likely person of interest or suspect" in those as well, Hartsock said.

According to the complaint, Syed denied any involvement in the killings during an interview with police on Tuesday.

How the investigation unfolded

Police first noticed similarities between the deaths of Aftab Hussein and Muhammad Afzaal Hussain, which took place days apart.

"We were able to relate the casings found on both the scenes that are likely fired from the same firearm," Hartsock said. "We quickly started looking at other cases that could be similar and identify that there might be a really active public threat."

The shootings spurred police to examine whether they were connected to a killing that happened November 7. That day, officers found an Afghan man, Mohammad Ahmadi, with a gunshot wound in the parking lot behind the business he ran with his brother.

As the investigation unfolded, a fourth killing happened just before midnight on August 5 in the area of Truman Street and Grand Avenue, where police found Naeem Hussain dead from a gunshot wound.

Police increased patrols near mosques and other areas and the governor sent state police to the city.

Police released images of a "vehicle of interest" that they said may be tied to the shootings. They asked for the public's help tracking down the silver sedan.

The city's Muslim community was on edge. Some stopped going to their local mosques or going out late a night, and some even avoided going out to shop for food.

At the same time, scores of tips began rolling in to law enforcement.

"We've had a total of about 230 tips," FBI Special Agent in Charge Raul Bujanda said Tuesday.

Residents also began voluntarily uploading surveillance videos from their homes to an online portal that was set up sp ecifically for the investigation. Police sifting through the footage found video that captured gunshots and vehicles leaving the scene, according to Hartsock.

A tip from the community eventually came in that led investigators to identify Syed as a suspect and track down the car.

Albuquerque police and the FBI got multiple tips about Syed and his vehicle, a Volkswagen Jetta, according to the complaint.

As police were waiting to execute a search warrant at the suspect's Albuquerque home Monday night, they saw him get into what they believed to be the same vehicle that had been linked to the homicides.

Officers eventually stopped the vehicle and detained Syed near Santa Rosa, New Mexico, more than 100 miles east of Albuquerque. That's when they saw firearms inside the vehicle, according to Hartsock.

Investigators executed a search warrant at Syed's home early Tuesday and found more weapons there, according to police.

"Multiple firearms were recovered from that home that are continually being tested. But right now we believe that at least one of them inside the home and one of them inside the car that was pulled over, are matching ... two crime scenes on Rhode Island and Cornell, and that is the basis of the charges that are going forward today," Hartsock added.

According to the complaint, Syed told police "he was driving to Texas to find a new place for his family to live because the situation in Albuquerque was bad. Muhammad then referenced the shooting of Muslims on the news."

Ahead of the suspect's arrest, police found records of Syed and one of his sons purchasing firearms and gun accessories from different shops in Albuquerque. Those purchases included a 9mm pistol bought on January 28, 2021, a scope for an AK-47 bought on August 1, and 7.62x39 caliber pistol and rifle bought on July 15, according to the complaint.

The document also notes that both 7.62x39 and 9mm "were the two calibers of weapon used in the above-mentioned homicides."

While searching the Jetta, police said they found a 9mm casing between the windshield and the hood of the car, and two 7.62x39 casings inside the vehicle, in addition to a 9mm handgun.

The 9mm casing found in the windshield matched with a casing found at the August 1 crime scene, according to the complaint.

Syed previously had "a few minor misdemeanor arrests (from the Albuquerque Police Department) from domestic violence" and some other incidents, Hartsock said. All three previous domestic violence charges Syed faced were dismissed, Hartsock said.

CNN was at the suspect's home

Hours before police announced Syed was a suspect, CNN was inside his home and spoke to his daughter, who offered insight on her father and what happened when they last saw each other, which was before his arrest and before authorities executed a search warrant on their family's home.

The daughter, one of Syed's six children, spoke to CNN Tuesday morning, while the family was cleaning up the mess left behind by investigators who had searched the house earlier that morning. CNN has chosen not to name the daughter out of concern for her safety.

"My father is not a person who can kill somebody. My father has always talked about peace. That's why we are here in the United States. We came from Afghanistan, from fighting, from shooting," she told CNN.

The daughter told CNN she married a man in February 2018, and her father was not happy with the marriage at the time but had come to accept it more recently. She said her husband was friends with two victims, Aftab Hussein and Naeem Hussain.