HOUSTON (CBSDFW.COM/AP) — The 5th U.S. Circuit Court of Appeals has rejected an appeal from a death row inmate who was part of the notorious “Texas 7” gang of escaped prisoners.

Attorneys for 56-year-old Patrick Murphy argued unsuccessfully to the court that evidence failed to show Murphy killed or tried to kill Irving police officer Aubrey Hawkins and that he had deficient legal help at his trial and earlier in his appeal.

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Mugshots of wanted armed convicts, who escaped from Connally Unit Prison, December 13, 2000. The convicts are top row L-R; Joseph C. Garcia, Randy Ethan Halprin, Larry Jame Harper and Patrick Henry Murphy, Jr. Bottom row, L-R; Donald Keith Newbury, George Rivas and Michael Anthony Rodriguez. (credit: Texas Department of Corrections/Newsmakers)

Murphy was serving 50 years for a Dallas sexual assault when he and six others broke out of a South Texas prison in 2000. They committed numerous robberies, including the holdup of what was then the Oshman’s Sporting Goods store where Hawkins was killed, before being captured in Colorado. One suspect killed himself there.

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Murphy is among three of the gang on death row. Earlier this year the Texas Department of Criminal Justice set an execution date for 45-year-old Joseph Garcia. He is set to die by lethal injection on August 30.

Three others have already been executed.

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(© Copyright 2018 CBS Broadcasting Inc. All Rights Reserved. The Associated Press contributed to this report.)