A former high school teacher’s former student has been accused of killing both her and their young son — born from an affair that made headlines in 2013 — a New York City police source tells PEOPLE.

An NYPD spokesperson declined to comment on the case, but the department source says Isaac Duran was charged Tuesday with two counts of murder in the deaths of former Dewitt Clinton High School teacher Felicia Barahona and her 4-year-old son, Miguel.

The 36-year-old mother and Afghanistan War veteran was found dead Monday morning in the living room of her Manhattan apartment, according to the police source, who confirms that she was strangled with an electrical cord and Miguel was drowned in the bathtub. The boy was found face-down, floating in the filled tub, the source says.

Their bodies were first discovered by the apartment building’s superintendent, who checked on Barahona after noticing a foul odor that seemed to be coming from her unit.

Duran was taken into custody later Monday, according to the source.

Under “intense questioning,” PEOPLE’s source alleges that Duran “owned up” to the killings — at one point “referencing Satan.”

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Duran’s custody status was not immediately available Tuesday afternoon. It was unclear from court records if he had been before a judge yet, entered a plea to his charges or whether a bail amount had been set for him.

It was unknown Tuesday if Duran had retained an attorney who could comment on his behalf.

According to the NYPD source, Duran initially denied having any involvement in the deaths and told detectives he hadn’t been to Barahona’s apartment building since 2012, when their son was born. However, police discovered that Duran was spotted on surveillance video entering and leaving the building over several days.

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Barahona’s relationship with Duran first became public in March 2013, after an internal investigative report was obtained by multiple local news outlets.

According to those reports, Barahona began having sex with Duran after he turned 18, though they later split in early 2012 before Miguel was born. Barahona was fired from Dewitt Clinton High in August 2012.

Her family could not immediately be reached.