Statement 1 is Incorrect: The Protocol against the Smuggling of Migrants by Land, Sea and Air is one of the three protocols that supplement the United Nations Convention against Transnational Organized Crime (UNTOC), not the UNCAC.

Statement 2 is Correct: The UNCAC is the first and only legally binding universal anti-corruption instrument. It was adopted by the UN General Assembly in 2003 and entered into force in 2005.

Statement 3 is Incorrect: Asset recovery is a fundamental principle and a specific highlight (Chapter V) of the United Nations Convention against Corruption (UNCAC), not the UNTOC.

Statement 4 is Correct: The UNODC is mandated by its member states to assist in the implementation of both the UNCAC and UNTOC. It also assists in the implementation of the three UN Drug Conventions of 1961, 1971, and 1988.