ALBUQUERQUE, N.M. (AP) — The son of an Afghan refugee suspected in the shooting deaths of four Muslim men in New Mexico will remain in custody pending trial on a charge that he allegedly provided a false address on a form when purchasing 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.

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.

“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.

Albuquerque police have charged Muhammad Syed, 51, with murder in the deaths of Aftab Hussein and Muhammad Afzaal Hussain. Hussein, 41, was slain on the night of July 26 after parking his car in the usual spot near his home. Afzaal Hussain, a 27-year-old urban planner who had worked on the campaign of a New Mexico congresswoman, was gunned down on the night of Aug. 1 while taking his evening walk.

The elder Syed is the primary suspect — but hasn’t been charged — in the death of Naeem Hussain and the slaying of Muhammad Zahir Ahmadi, a 62-year-old Afghan immigrant who was fatally shot in the head last November behind the market he owned in the city.

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.

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

John Anderson, Shaheen Syed’s attorney, did not return messages seeking comment but 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.

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.

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.

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.