The family of the Massachusetts mother of four found dead inside her home over the weekend is urging her “coward” husband to turn himself into the authorities as the search for the “armed and dangerous” suspect enters its second day.

“He better turn himself in. He needs to stand up for what he did, and turn himself in. And not be a coward,” Brooke Pertile told Boston 25 News of her brother-in-law, Aaron Pennington.

Aaron, 33, has been the subject of a desperate manhunt since Sunday, when his wife, Pertile’s older sister Breanne Pennington, was discovered with a fatal gunshot wound to the face at their Gardner home.

He may have a firearm and is considered  “armed and dangerous,” the Massachusetts State Police wrote in an update Tuesday morning.

“He needs to turn himself in. He needs to do it for the kids,” Pertile insisted.

The grieving sister said that Aaron had Mental Health Issues that scarred the family of six’s seemingly idyllic suburban life.

“He, on the outside, he was a very nice person. But he’s been struggling with some mental health issues. They just were getting worse,” Pertile explained.

Aaron and Breanne’s marriage was struggling, and Breanne even planned to move with their four children – ages two, five, seven, and nine – to Texas in order to get away, a criminal complaint in the case previously revealed.

Aaron – who spent eight years in the US Air Forces and now holds “active secret clearance” with Raytheon Missiles & Defense, according to LinkedIn – threatened to take his own life in the past, police added.

“She’s a very loving, caring, compassionate woman. She always saw the best in everything and people,” Pertile said of her late sister.

“She definitely lit up the room like no other, any room that she walked in.”

Despite the troubles in the marriage, however, relatives never suspected or anticipated violence in the Pennington house, she added.

“We’re all in shock about this. We’re all in shock. We had no idea something like this would ever happen,” Pertile – who spoke with Breanne just three days before the alleged killing – told Boston 25.

At the time of her death, Breanne was even looking forward to raising chickens in her backyard, Pertile added.

Breanne’s body was discovered in an upstairs bedroom Sunday morning after her children ran over to a neighbor’s house asking for help, the criminal complaint stated.

“Four children came over to her house scared because they could not find their father and their mother was in her bedroom crying,” a trooper reportedly wrote of the grisly find.

Surveillance footage later revealed Aaron supposedly fleeting the scene around 8:50 a.m..

Shell casings were found at the scene, but no weapon, according to WCVB.

Breanne was known to have a gun in the home for protection, police documents allegedly noted.

Authorities found Aaron Pennington’s white 2013 BMW Monday afternoon at a Boy Scout camp in Gardner, the Massachusetts State Police confirmed.

After an extensive search of the area with K9 dogs, however, the troubled father of four remained elusive.

The part of Gardner that is near the wooded area where the car was found was also placed under a shelter in place order, which has since been lifted.

Aaron Pennington is described as a white male who is 6’2” and about 175 pounds with blonde hair and blue eyes, authorities said.

Anyone who sees him is advised not to approach him, but instead to call 911 immediately.