The call came in just before midnight from a stately home in Fallston, from one of the couple's children reporting that their mother had been gunned down inside her own home.
"Deputies responded and found the wife had suffered several gunshot wounds, and unfortunately this morning around 8 o'clock she passed away," Harford County Sheriff Jeffrey Gahler said.
48-year old Lara Muscolino had worked for more than a decade helping to save lives as a certified registered nurse at MedStar Union Memorial Hospital in Baltimore.
Her husband, 54-year old Ricardo Muscolino, had already fled from the home when deputies arrived, but he didn't go far.
"About the same time as the call, the medical call for service and the deputies responding to the residence, he actually walked into the Northern Precinct and presented himself to our duty officer there," Gahler said.
Police say deputies had responded to the home before for some minor service calls, but nothing domestic-related, which would hint at ongoing problems between the couple.
At this point in the investigation, police aren't saying where inside the home that the shooting occurred or how their eldest daughter discovered her mother once she had been wounded.
"The couple's three children were in the residence and one of them dialed 911 to seek medical assistance, so who witnessed? Again, any loss of life is horrible and especially in domestic situation like this, but to have the children there and involved makes it even worse if that's possible," Gahler said.
Ricardo Muscolino is being held in the Harford County Detention Center.
He faces a series of charges including first degree murder.
Anyone with information is asked to call Det. Seth Culver at 443-409-3498, or Metro Crime Stoppers.