Maryland Man Accused of Fatally Shooting Woman, then Killing Son, 7, to Prevent Him from Talking

Facebook (2) Jennifer Jeffrey and her son, Kester Browne

Federal authorities have charged an alleged Maryland drug dealer with the 2015 killings of a 31-year-old mother and her 7-year-old son, PEOPLE confirms.

Last week, investigators arrested Andre Ricardo "Poo" Briscoe, 37, on federal drug distribution charges as well as several other counts: use of a firearm to commit murder in relation to the drug trafficking crimes, killing a witness to prevent communication with law enforcement and being a felon in possession of a firearm and ammunition.

A statement from the Department of Justice alleges Briscoe killed Jennifer Jeffrey and her son, Kester Browne, during a May 27, 2015, armed robbery.

"From March through October 2015, Briscoe conspired with others to distribute heroin," reads the statement. "The indictment alleges that on May 27, 2015, in connection with his drug distribution, Briscoe committed an armed robbery and during the course of the robbery shot and killed Jennifer Jeffrey and Jeffrey’s seven-year-old child."

Jeffrey was killed first, and her son, authorities allege, was killed because he'd witnessed it.

"The indictment also alleges that Briscoe shot the child multiple times, including in the head and mouth, killing the child to prevent him from communicating with law enforcement," the statement says.

"These murders are shocking and unconscionable," the statement quotes U.S. Attorney Rob Hur as saying. "This indictment should make one thing crystal clear: If you touch a witness, especially a child, the full weight of federal law enforcement will be harnessed to find you and bring you to justice. And we will not stop investigating until we bring to justice anyone else who was involved."

PEOPLE was unable to reach Briscoe’s attorney, William Purpura, for comment, but he spoke to the Baltimore Sun, and questioned why the charges were filed now, just before a statute of limitations deadline.

"It's kind of perplexing and mysterious and concerning to Mr. Briscoe," Purpura told the paper.

There is no statute of limitations for murder, but the killings are connected to federal drug trafficking charges, which are subject to the filing time limits.

Briscoe has yet to enter pleas to the charges.

He faces either death or life in prison if convicted, the statement indicates.

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The Sun notes that, in a court filing last month, Judge Richard D. Bennett outlined several facts of the case, including an allegation that Jeffrey "was a heroin dealer and that Defendant Briscoe was her weekly or twice weekly customer."

Purpura told the paper he intends to prove his client was in a different city at the time of the murders.

"There's going to be an issue of when the killings actually occurred," Purpura said.