"The punishment of those who wage war against Allah and His Messenger, and strive with might and main for mischief through the land is: execution, or crucifixion, or the cutting off of hands and feet from opposite sides, or exile from the land: that is their disgrace in this world, and a heavy punishment is theirs in the Hereafter." -- Qur'an 5:33
Generally when Islamic supremacists carry out a crucifixion, they do so on the already-dead body of an executed person.
Sharia Alert from the Kingdom of Misunderstanders of Islam: "Saudi Arabia Beheads and Nails Murderer's Body to Cross," from NewsCore, June 21 (thanks to Sr. Soph):
Saudi Arabia executed two murderers including a Yemeni whose body was nailed to a cross after he was convicted of killing a fellow countryman and his daughter, the interior ministry said on Monday.
Shaaban al-Nasheri was beheaded for shooting dead Dhayeh al-Manbahi after barging into his family home in the southwestern town of Jazan, the ministry said in a statement cited by the official SPA agency.
Nasheri was also found guilty of raping and killing Manbahi's daughter before shooting and wounding her sister.
Following his execution, the murderer's body was nailed to a cross in Jazan.
In the second case, Saudi national Mohammed al-Zahrani was decapitated in El-Baha, in the southwest, for shooting dead compatriot Said al-Zahrani over a land dispute.
The beheadings bring to 15 the number of executions reported in the ultra-conservative Gulf monarchy this year, according to an AFP count. In 2009, there were 67 reported executions in the kingdom, compared with 102 in 2008.
Memo to NewsCore: conservatives, even "ultra-conservatives," do not generally behead anyone.
Rape, murder, apostasy, armed robbery and drug trafficking are all punishable by death under Saudi Arabia's strict Islamic law. In extreme cases, the convict is executed and his body crucified in public.