The shooting happened around 2:20 a.m. Sunday inside a home on Meredith Road.
On Monday, the Montgomery County District Attorney's Office announced an arrest warrant for 42-year-old Kelvin Roberts, of Philadelphia. He is facing charges of second-degree murder, robbery, burglary and other related offenses.
Authorities believe at least two suspects, including Roberts, broke into the home and shot Andrew Gaudio, 25, and his mother, Bernadette Gaudio, 61.
Andrew was pronounced dead at the scene. His mother was taken to Lakenau Medical Center, where she remains in critical condition.
"We are hopeful she will survive," said DA Kevin Steele during a Monday news conference.
WATCH: Montgomery County District Attorney's Office provides update on deadly home invasion
Montco DA provides update on deadly home invasion
Steele says Bernadette was able to call 911 after being shot. In the background of the call, her attackers could be heard rummaging through the house, according to a criminal complaint filed Monday.
Officials believe they got in through the basement.
"The son Andrew who was killed, I believe he fought back and tried to help his mom in the circumstance. Again, this is a terrible, terrible case," Steele said.
A white Hyundai Azera allegedly being driven by Roberts was captured on the dashcam video leaving the scene when officers arrived. The dashcam video also reportedly captured the victim's green Jeep Cherokee being driven away from the scene.
A check of the Hyundai led officers to a home on Sansom Street in Philadelphia, where officers found the stolen Jeep and Bernadette's jewelry box after executing a search warrant, Stelle said.
A motive for the crime is still being investigated.
Steele called those involved "dangerous" and urged the public to come forward with tips.
"We're dealing with dangerous people here and we need the public's help, and anybody that knows where they are to help us find the individual or any information that would help us find other individuals that's involved in this," he said.
Neighbors are devastated for the family.
"It's heartbreaking for the family. It's heartbreaking for the community," said another Wynnewood resident.
"I hope the family knows they can lean on any of us and reach out to any of us and we'll be there to help," said one neighbor.
"I'm sad for the family, and that's the only thing I can think of right now is that person's family, particularly around the holidays," said one neighbor, Sergio Johnson.
A $5,000 reward is being offered for information that leads to an arrest.
Anyone with information is asked to call the Lower Merion Police Department at 610-278-3386 or the Montgomery County Detective at 610-278-3386.