John Allen Muhammad has been executed by lethal injection for a string of sniper killings around Washington DC in 2002. What is known about the 48-year-old Gulf War veteran, and his motivations for carrying out such a shooting spree?
John Allen Muhammad never explained the shootings
Thanks to a tip-off from an alert citizen, police arrested Muhammad and 17-year-old Lee Boyd Malvo as they slept in their car at a Maryland rest stop on 24 October 2002.
It brought to an end a three-week reign of terror that saw 10 people killed and three injured in Washington DC, Maryland and Virginia.
The victims had been simply going about their business - shopping, filling up with petrol or sitting by a bus stop - when they were picked off by the gunmen in what became known as the Beltway sniper attacks.
Malvo, who is now serving a life sentence, later testified that the pair had planned to shoot six people a day, and extort $10m from the authorities that would be used to train homeless children to terrorise other cities.
Born John Allen Williams in New Orleans in 1960, Muhammad changed his name after converting to Islam. He was a member of the Nation of Islam.
He enlisted in the Louisiana army national guard at the age of 17 before volunteering for active duty, which saw him serve in the first Gulf War.
Muhammad had a "million-dollar smile and flashes of temper," his commanding officer in Louisiana, Rafael Miranda, remembers.
But Muhammad's military service was described as unremarkable, and he was discharged in 1994, having made the rank of sergeant.
His first marriage was to teenage sweetheart Carol Williams, with whom he had a son.
She described him as outgoing with "a good sense of humour". "He wasn't a quiet type. He liked to talk, he liked to mingle with people," she said in a newspaper interview at the time of his arrest.
They divorced in 1987, and a year later went on to marry Mildred, with whom he had three children.
Friends who lived close to the couple in Tacoma, Washington state, said the couple initially appeared to have a great relationship and a solid family life.
But as his attempts to set up a karate school and a car-repair business foundered during the 1990s, so, too, did his marriage.
Muhammad's ex-wife believes he intended to kill her
By 2000, they were divorcing and Mildred Muhammad had applied for a restraining order saying she was afraid of him. "He is behaving very, very irrational. Whenever he does talk with me he always says that he's going to destroy my life," she wrote.
Muhammad reportedly took the children to the island of Antigua without her permission, and when they returned she was granted custody of the children and moved away to Maryland.
Mildred Muhammad, and the prosecution at his trial, maintain that his ultimate goal was to kill her and regain custody of the children. They argued that the serial killings were an attempt by Muhammad to distance himself from her eventual murder.
It was in Antigua that Muhammad met the then 15-year-old Jamaican-born Malvo, whose father had abandoned him and whose mother would leave him for months on end with relatives and friends.
His mother, Una James, said in 2003 that she had not had an intimate relationship with Mr Muhammad but that he and her son had eventually formed a strong bond.
Malvo testified against the man he once called 'father'
When she moved to Florida around 2001, she left her son with Muhammad because he was supposed to join her a few months later.
Malvo did go to Florida, for a short time, before moving to Washington state, where he and Muhammad spent time in a homeless shelter in Bellingham before moving to Tacoma.
Reports said the pair were very close, with Muhammad referring to the teenager as his son and the teenager calling Muhammad his father.
They would spend hours playing chess in a coffee shop in Bellingham.
"They were kind of a weird pair, always keeping very much to themselves and never talking to others," Mark Wendover, assistant manager of the Stuart coffee house in Bellingham, said.
Neighbours in Tacoma reportedly said they often heard guns being fired in the garden at night.
In November 2004, John Allen Muhammad was found guilty by a Virginia court of murdering 53-year-old Dean Harold Meyers at a gas station in Manassas, and sentenced to death.
While on Virginia's death row, he was extradited to neighbouring Maryland where he was convicted of six counts of murder in 2006.
During his trial in Maryland, Muhammad acted as his own lawyer and in opening statements said he would prove his innocence. However, he never really argued his case, even when he had to cross-examine his former accomplice.
On the witness stand, Malvo admitted lying at the earlier trial in Virginia, saying he said he was the sole shooter in order to protect Muhammad from a potential death sentence, as it is more difficult to obtain the death penalty for a minor.
During his two days of testimony, Malvo gave many very detailed aspects about the three-week shooting spree, including the fact that he fired three of the shots and Muhammad fired 10.
He later confessed that the pair were responsible for at least four other killings elsewhere in the US, although Muhammad is not believed to have commented on this.