A Mexican national on death row in the US, has been executed despite Mexican authorities pleading for his life to be spared. <br /><br />Ruben Cardenas was given a lethal injection at the Texas death chamber in Huntsville for the rape and strangling of his 16-year-old cousin more than 20 years ago.<br /><br />He told investigators he was high on cocaine at the time.<br /><br />The Cardenas case drew protests from Mexican diplomats, who said Texas prosecutors did not follow due process and did not let Cardenas speak with Mexican consular officials.<br /><br />U.S. authorities apparently neglected to notify Mexico about the arrest and failed to hold a review required by the United Nations’ international court in The Hague.<br /><br /> Texas executes more criminals than any other U.S. state which has long caused friction with Mexico, which has no death penalty. <br /><br />It was the 23rd execution this year in the US compared to 20 in 2016 and 28 in 2015.<br />