Convicted Washington sniper John Allen Muhammad has come face-to-face with his young accomplice Lee Boyd Malvo at a second murder trial in Maryland.
Malvo was 17 at the time of the Washington killings
Muhammad, 45, is accused of six counts of murder in Montgomery County, just outside Washington DC, in 2002.
In 2004, he was sentenced to death by a court in neighbouring Virginia after he was convicted of one fatal shooting.
Malvo, now 21, was jailed for life in Virginia. He has agreed to testify against Muhammad and to plead guilty.
Prosecutors in Rockville, Maryland, have said they are pursuing the second trial in case the Virginia convictions are overturned on appeal.
They also say they want to serve justice in Montgomery County, where six of the 10 killings took place in October 2002.
Malvo, wearing a dark sportscoat and white shirt, appeared to be nervous as he prepared to face his older partner for the first time in more than two years.
Muhammad has chosen to represent himself during the trial
Muhammad still calls Malvo "my son" and told the jury in the trial's opening statements earlier this month that he would prove the pair's innocence.
After being sworn in, Malvo was asked to identify Muhammad, which he did.
In his testimony, he said that Muhammad had told him before the shootings that they would "terrorise this nation".
He said Muhammad also had planned to carry out six shootings a day for a month, and then target schools and children's hospitals.
Prosecutors were questioning Malvo, apparently aiming to portray Muhammad as a predatory figure who had brainwashed Malvo and turned him into a killer.
"Did you tell him you loved him?" Malvo was asked.
"Yes," he answered.
"Did he tell you he loved you?"
"Yes," Malvo responded.
Malvo was called as a witness in the Virginia trial, but refused to testify.
In the second trial, Muhammad has chosen to represent himself and so far has revealed little about how he plans to convince jurors of his innocence.