asesinar

The standard verb for "to murder" — a deliberate, premeditated killing, stronger and more specific than matar ("to kill" in general, which covers accidents, self-defense, animals, etc.). Asesinar always implies unlawful, intentional homicide.

• Al político lo asesinaron a la salida del hotel. — The politician was assassinated as he left the hotel.
• La policía investiga quién asesinó a la víctima. — Police are investigating who murdered the victim.
• La novela gira en torno a un crimen: alguien asesinó al mayordomo. — The novel centers on a crime: someone murdered the butler.

Using asesinar interchangeably with matar — asesinar specifically implies premeditated, unlawful killing (murder or assassination), so el león asesinó a la cebra ("the lion murdered the zebra") sounds wrong; matar is the correct, neutral verb for that.

• song La funcionaria asesina — A 1986 new-wave single by Spanish group Alaska y Dinarama (from the album No es pecado), written by Carlos Berlanga and Nacho Canut, about a bored civil servant who becomes a serial killer — widely regarded as one of the songs that made Alaska an icon of Spanish 1980s pop.
• song Hoy voy a asesinarte — A 1982 song by Galician band Siniestro Total, from their debut album ¿Cuándo se come aquí?, an adaptation of Tony Hatch's "The Life and Soul of the Party" with new Spanish lyrics about jealousy and betrayal.