Americans danced in the streets over the death of al-Qaeda leader Osama bin Laden. The killing of his successor has been met with a more muted response - but those robbed of their loved ones by Ayman al-Zawahiri's actions say his death matters too.

On 11 September 2001, roughly five seconds before American Airlines Flight 11 hit the north tower of New York's World Trade Center, the plane flew directly over Charles G Wolf's apartment building.

Trained as a pilot, Mr Wolf, 68, knew instantly that a twin-engine plane was flying dangerously low at full throttle through Manhattan - and his worst fears were soon validated.

The hijacked flight crashed directly into the building where Katherine, his Welsh-born wife of 13 years, worked. She was among 2,977 people who died that day.

Mr Wolf - who rushed out onto the street to get a closer look as he frantically called his spouse - fell ill from the toxic fumes of the wreckage.

"I got hit twice, you might say," he said, referencing the death of his wife and his nearly decade-long health issues following the attack.