A teenager accused of killing his 16-year-old sister stood with his shoulders slumped and head bowed as charges were read against him in adult district court.

Family members quietly wept as Sergei Carlson, 15, was charged Wednesday with murder and a deviate sexual act in the death of Fargo South High School student Whitney Carlson. Sergei Carlson, a Wisconsin resident, was transferred to adult court Tuesday.

Authorities said Sergei Carlson told police he strangled Whitney Carlson with his hands and put pillows over her head to muffle her sounds, then had sexual contact with her.

Family spokesman Mark Bourdon said it was difficult for relatives to hear East Central District Judge John Irby outline the charges.

"We knew this day was coming," Bourdon said. "You can't really prepare for it."

Sergei Carlson was not asked to enter a plea on the felony murder charge. He pleaded not guilty to the sex charge, a misdemeanor. Bond was set at $250,000 and a preliminary hearing scheduled for Oct. 25.

Cass County prosecutor Tracy Peters said in an interview that lawyers have received results from a psychological evaluation on Sergei Carlson, but she "wasn't in a position" to talk about them. Another evaluation could be ordered now that Carlson has been transferred to adult court, Peters said.

Bourdon said the family had no idea that Sergei "was harboring thoughts" that led to the charges against him.

"I don't believe we'll come to terms with that for some time," he said.

Bourdon was asked if he thought Sergei Carlson has shown remorse.

"That's a hard one because it's so subjective," Bourdon said. "Has he shown sadness? Yes, I think it's fair that I can say that. Beyond that, I can't say."

Bourdon said Sergei Carlson was adopted from Russia when he was 7 years old. He moved with his father, the Rev. Scott Carlson, to Wisconsin in 2002. Whitney Carlson lived with her mother in Fargo.

The complaint said Sergei Carlson, who was visiting the family in Fargo, was watching TV when Whitney returned home on the night of July 13. He told police the two of them had a brief conversation before Whitney went to her bedroom. Sergei Carlson told police he went to her bedroom about an hour later and killed her.

Bourdon said the family had received some information about the case to prepare them for court proceedings. That didn't make Wednesday's hearing any easier, he said.

"On one hand in this situation, you want information and detail," Bourdon said. "On the other hand, you don't."