Physically Disabled, Victims of Crime?

Today, the New York Times posted an article that I felt would be of interest and I would love to get other people's feedback as well.

The Justice Department has just released a study claiming that disabled people are more likely to be victims of crime than non-disabled people. I guess this would make sense, but the article makes the bigger picture unclear, leaving me with lots of unanswered questions.

In a survey done in 2007, 716,000 disabled people were victims of sexual assault and/or rape and nearly 2.3 million were victims of crimes, such as burglary and motor vehicle theft, according to the article.

It also states that the survey made it unclear, the physical status of these victims and to what extent, their disabilities played a role.

So, here are my question:
How valid are these findings?
What types of disabilities do these "victims" have?
In what ways does their disability play a role in their victimization?
Are they being targeted simply because they are less likely to fight back due to disability?
Are they saying disabled people cannot defend themselves?

What does everyone else think? It may not be completely false, but I need a more detailed credible report