From NewScientist:
Using DNA from many half-siblings
could produce a DNA match of greater
than 90 per cent confidence, but it
would be difficult to get as high as
99.9 per cent without a closer relative says Rhonda Roby, a forensic
geneticist at the University of North
Texas Health Science Center, Fort
Worth.
Roby, who led the team using DNA
evidence to identify the remains of
people killed in the 9/11 attacks in
2001, says that the statistical
analysis based on DNA from
half-siblings is more complex and less
reliable than analysis based on DNA
from a closer relative like a parent
or child.
There are reports that one of bin Laden's sons was also killed in the raid.
Roby says DNA from a son and several
half-siblings could confirm Osama's
identity with 99.9 per cent accuracy.
If, however, the government was able
to obtain DNA from bin Laden's body,
his son and also that son's biological
mother – who might have been at the
compound during the raid, it could
perform DNA profiling with a "full
paternity trio", assuring 99.9 per
cent accuracy, Roby says.
According to ABC:
DNA collected from bin Laden's body
Sunday was compared to DNA from
multiple relatives, a U.S.
intelligence official told ABC News.
The U.S. is believed to have collected
DNA samples from bin Laden family
members in the years since the 9/11
attacks that triggered the U.S.-led
invasion of Afghanistan.
The New York Times says the same:
Officials said they collected multiple
DNA samples from Bin Laden’s relatives
in the years since the Sept. 11
attacks.
Bin Laden did not have any full siblings. He did have more than 50 half-siblings, some of whom have close ties to the United States and had long ago distanced themselves from him.
Christie Wilcox explains in a Scientific American article how the get a DNA fingerprint and that nowadays it takes only a few hours.