A 19-year-old New Jersey man will appear in court Monday after being charged with shaking his girlfriend's baby to death, according to the Atlantic County Prosecutor's Office.

Daquan Davis is charged with manslaughter and endangering the welfare of a child.

Police say Davis was caring for the 6-month-old infant Friday morning at School House Apartments on North Martin Luther King Boulevard in Atlantic City, N.J., while the child’s mother was at work.

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Police say when she returned home around 4 a.m., she found her son unresponsive and called police. The baby was pronounced dead. Investigators believe Davis shook the baby, causing his death.

In an NBC10 exclusive interview, the child’s mother, Ebony Stewart, described the horrific discovery she made when she returned home.

“I noticed my son wasn’t breathing. I looked closer and he wasn’t breathing. His face was purple and frozen cold.”

Stewart said Davis acted as if nothing had happened.

“He sat there saying, 'Everything will be alright …We’re in this together … I know you’re hurting. I am here for you,'" Stewart said.

One of the woman's neighbors appeared rattled by the news: "I live in this building, and that same little baby, just two weeks ago, I told the mom how cute the baby was. And just to hear this, right now, I don't know what to think, I really don't,” Lloyd Phillips told NBC's Atlantic City affiliate.

Davis is currently being held on $750,000 bail.

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