The son of a New Mexico man suspected of gunning down four Muslim men over the course of several months will remain in custody pending trial for allegedly using a bogus address to buy a gun last year.

Shaheen Syed, 21, appeared in U.S. district court in Albuquerque on Monday, with the judge granting a motion by federal prosecutors to keep him behind bars pending the ongoing investigation into the deaths of four Muslim victims dating back to November 2021. 

His father, 51-year-old Muhammad Syed, has so far been charged with murder for two of the slayings – the deaths of Muhammad Afzaal Hussain and Aftab Hussein. – but officials have called him the "most likely" suspect in the murders of Naeem Hussain and 62-year-old Muhammad Zahir. With the help of an interpreter, he "denied having any involvement in the murders in this case," the criminal complaint alleges. 

The four men – all Muslim and from South Asia – were ambushed, shot, and killed in Albuquerque since November 2021. 

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father and son in Muslim men killings

Shaheen Syed, left, possibly helped his father, Muhammad Syed, right, surveillance one of his alleged victims.  (U.S. District Court/AP)

The most recent murder took place on Friday evening, when Naeem Hussain, from Pakistan, was discovered fatally wounded in the area of Truman Street and Grand Avenue. 

On Aug. 1, the third victim, local city planner Muhammad Afzaal Hussain, 27, was gunned down in the area of Cornell Drive Southeast and Garfield Avenue Southeast, police said. 

ALBUQUERQUE POLICE RELEASE BODY CAM VIDEO OF MAN SUSPECTED OF MURDERING MUSLIM MEN BEING ARRESTED 

And before then, 41-year-old Aftab Hussein was fatally wounded on July 26, 2022. According to the criminal complaint, Syed "waited behind a bush, north of the driveway where Aftab Hussein would park his vehicle."

victim photo of Muhammad Afzaal Hussain

This undated file photo released by the City of Española shows Muhammad Afzaal Hussain, 27, a planning and land use director who was killed in Albuquerque, N.M., on Aug. 1, 2022.  (City of Española via AP, File)

A ShotSpotter activation showed 13 gunshots were fired, following by additional rounds, in the area of 417 Rhode Island Street, police documents show. There, officers discovered Aftab Hussein "lying next to a silver Hyundai sedan at" nearby, with multiple apparent gunshot wounds. 

Several months before that, on Nov. 7, 2021, 62-year-old Mohammad Ahmadi was discovered shot and killed in the rear parking lot of a halal café he owned with his brother on San Mateo Boulevard, according to city officials and local affiliate KRQE-TV. 

In their motion, prosecutors pointed to cellphone records that they say show Syed possibly helped his father track Naeem Hussain, a 25-year-old man from Pakistan who was fatally shot on Aug. 5 in the parking lot of a refugee resettlement agency in southeast Albuquerque.

Man cries over grave of murdered brother

Altaf Hussain cries over the grave of his brother Aftab Hussein at Fairview Memorial Park in Albuquerque, N.M., on Friday, Aug. 5, 2022. (Chancey Bush/The Albuquerque Journal via AP)

"The evidence that agents have been able to gather thus far in this rapidly unfolding investigation is obviously alarming with respect to the defendant’s short and frequent communications with his father both before and after the murder of Naeem Hussain," the motion stated.

Court documents filed in federal court provided more details about Naeem Hussain's killing, saying it appeared he had been followed to Lutheran Family Services, the resettlement agency, following funeral services for two of the other shooting victims. Shots were fired at his SUV around 4 p.m., striking him in the head and the arm.

Prosecutors claim that Shaheen Syed spoke with his father when his phone was somewhere in the general area of the Islamic Center of New Mexico and soon after his father’s phone pinged in an area that included Lutheran Family Services.

After Hussain was fatally shot, Shaheen Syed’s phone moved to an area closer to the crime scene, according to the motion. Ten minutes after the shooting, the motion states the men shared a second call as their phones remained in the "general area of the murder."

Syed’s attorney argued that prosecutors gave no indication of the size of the area that his phone was in relative to the shooting.

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The Syed family home is a few minutes drive from both the Islamic Center and Lutheran Family Services.

John Anderson, Shaheen Syed’s attorney said in court filings that the allegations against his client were "thin and speculative."

"The United States’ motion boils down to an effort to detain defendant for a crime with which he has not even been charged," Anderson argued, referring to the slayings of the Muslim men.

Anderson also included a photo of a Florida driver’s license issued to Shaheen Syed in 2021, contradicting prosecutors' claims that he misrepresented himself as a Florida resident while making a purchase at an Albuquerque gun store.

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Prosecutors also presented prior police reports of Shaheen Syed allegedly beating his father and sister and an unrelated incident in which he and his brother were allegedly involved in a shooting outside a Walmart.

Muhammad Syed arrest bodycam video

FILE - This Aug. 9, 2020, still image taken from officer video provided by the Albuquerque Police Department shows the arrest of Muhammad Syed. Syed, the main suspect in the slaying of four Muslim men in Albuquerque has committed regular acts of violence in the six years since he fled war-ravaged Afghanistan and resettled in the United States, according to police documents and court records.   (Albuquerque Police Department via AP, File)

Court documents state that two guns purchased by Syed and his father at an Albuquerque gun store in July had been partially painted white. The guns were seized during a search of the family's home; and testing determined bullet casings found at the July 25 and Aug. 1 shootings matched the rifle that belonged to Muhammad Syed.

Casings found at one of the crime scenes also matched a handgun found in the elder Syed's vehicle when he was taken into custody, according to a criminal complaint.

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Muhammad Syed is scheduled to appear before a state district judge Wednesday as prosecutors seek to have him detained without bond pending trial on the two counts of murder.

Fox News' Danielle Wallace and The Associated Press contributed to this report.