This is off topic from the original thread, but he was the mayor of the city and felt that his police force could do a better job by focusing on dangerous criminals and traffic safety. Imagine if HPD started capturing undocumented immigrants. That would mean a police officer trying to take care of a routine traffic stop would suddenly be involved in a high speed chase that would put everyone's lives in danger if the driver of the vehicle was an undocumented immigrant. Imagine trying to be a detective, investigating a murder in a community where everyone was afraid the cops were going to deport them. Imagine the crime and hostility that could result against local law enforcement if local residents had family members deported by HPD.
As I said before, Bill White was a pragmatist who felt that his job as mayor was to make the city run as smoothly, peacefully, and prosperously as possible. He is not an ideologue, so even if he opposed illegal immigration, he is not the kind of person who would send a city into chaos in order to achieve that goal. Again, while I disagree with him on several issues, I think we could all respect that type of pragmatic style of governing because it actually works. It certainly works a lot better than the ideology generated stuff that possesses most politicians who care more about their party and they ideology than about the wellbeing of the people.