Conrad Murray Under Investigation in TX

Dr. Conrad Murray's Houston, TX patients may be interested .... the Texas Medical Board is investigating the good doc.

DEA sources tell TMZ its investigation into Dr. Murray's prescribing practices in connection with Michael Jackson is still active. When the DEA investigates a TX doctor ... the DEA contacts the Texas Medical Board and that routinely triggers a Texas Medical Board investigation.

And law enforcement sources tell us the Texas Medical Board has been working with the DEA on the Conrad Murray probe.

Dr. Murray's rep could not be reached for comment.