WESTERVILLE, OH (WCMH) — A former doctor, who plead guilty to drug, tax and fraud charges earlier this year is in critical condition after suffering at least one gunshot wound in an apparent home invasion.

The Franklin County Sheriff’s Office said that victim is Kevin Lake, 51.

His son called 911 at 7:12 a.m. on Thursday morning.

“I heard gunshots downstairs and my dad’s not responding. We had an intruder the other night,” he said in the 911 call.

He identifies himself as Jonah Lake, 19, to the 911 operator. He said his mother had already left for work.

“They threatened us,” he said. “We got a letter and he tried to tell the police, but they wouldn’t listen!”

Jonah said he and his family had been carrying guns on them at home for protection.

“The son appeared to be hiding himself upstairs and informed our 911 that he did indeed have a gun for his protection,” said Major Steven Tucker with the Franklin County Sheriff’s Office.

Major Tucker said they’re looking in to the criminal past of the victim.

“It’s my understand he’s had some involvement with the criminal justice system over the last several years,” he said.

According to the U.S. Department of Justice, Kevin Lake pleaded guilty to running a pill mill on S. High Street in Columbus and evading $3.5 million in taxes. He had admitted to knowing that doctors and staff at his clinic were prescribing painkillers with no legitimate medical purpose.

Investigators are still trying to figure out who shot him.

“It does appear that there’s at least one window where there may or have may not been a possible forced entry,” said Major Tucker.

He advised neighbors should lock their doors and windows.

“If indeed this is a home invasion that happened at early morning hours, that’s something that they community needs to pay very, very close attention to and obviously safeguard their residence,” said Major Tucker.Keep checking NBC4i.com for real-time updates on this story. To get alerts for breaking news, grab the free NBC4 News App for iPhone or Android. You can also sign up for email alerts.