SIOUX FALLS, S.D. (AP) - A Sioux Falls man held without bond after being accused of strangling his wife and 7-month-old son displayed unusual behavior two days before the deaths, according to a police affidavit.

In court on Monday, a lawyer for Brian Leingang, 33, entered not guilty pleas for his client to charges of first-degree murder.

Leingang's wife, Melissa Leingang, 38, and son, Caden, were found dead in their Sioux Falls home Friday night.

Leingang, raised in Mandan, N.D., attended Mandan High School as a freshman, according to school records, said MHS principal Mark Andresen. But beyond freshman year, there are no records and Andresen said he doesn't know if Leingang stopped going to school or transferred to another school.

The affidavit describes odd behavior by Leingang after an accident last Wednesday in Sioux Falls.

Leingang's car hit a pole and continued through an intersection before crashing into a porch. Leingang seemed confused and did not respond when asked if he needed help, said Jennifer Scheaffer, who lives at the house that was damaged.

Joe Pulliam, who drove past the scene moments later, said he saw the driver leave the car, run back to the house and lay down on the damaged porch.

"I shook him a couple times, and he sat up. He looked disoriented," Pulliam said. "Then he jumped back up and ran away again."

Pulliam followed the driver to a trailer and watched him leap into a window and out the back door. He approached Pulliam's truck and accepted a ride back to the accident scene, according to the affidavit.

Officers accompanied Leingang to a hospital to be checked for injuries and be tested for drugs, police spokesman Loren McManus said. Tests found no alcohol or drugs in his system.

"If the officers felt there was something else going on, they could place somebody on a mental health hold," McManus said.

After leaving the hospital, Leingang was booked into Minnehaha County Jail. A mental health screening there also didn't indicate problems.

"There must not have been any red flags," warden Tim Devlin said. "If there would have been any concerns about his mental health, they would have notified a nurse."

The affidavit also said Leingang had told police at the scene of the slayings Friday that the devil had tricked him.

Police went to the home after a 911 call. According to court papers, Leingang said by phone to a relative in another state, "I just killed everyone in my family."

When police arrived, Leingang was standing in the living room in his underwear. His wife's body was just inside the door; police found the boy dead in a bedroom, according to court papers.

At his arraignment, Leingang gasped "I'm sorry" to his 13-year-old stepdaughter. Deputies restrained him after his lawyer tried to stop him from speaking further.

Prosecutor Hope Matchan said Leingang's statements during the hearing might be used against him. "I know what I heard," Matchan said.

"My mind's going a million miles an hour for my daughter," Marty Halouska, Melissa Leingang's ex-husband, said in a telephone interview.

"She was a great person all around. Just a perfect person," said her brother, Chuck Mischel.

Her children were her life, he said. "She just loved taking care of her kids. She was just so motherly and good with them all the time."

She got a divorce about 10 years ago and married Leingang about five years ago.