Muciño was born in Jasso, Hidalgo where he played in Cruz Azul's youth academy until his debut with the senior team in 1969.

At the time of his death, Muciño was regarded as a key player for the Mexico national football team alongside Enrique Borja.

[1][2][3] In the early hours of 31 May 1974 Muciño was shot 3 times outside of a restaurant by 32-year old Jaime Antonio Muldoon Barreto, an engineer with whom he had a physical confrontation earlier in the evening.

His father, Roberto Muciño Martínez, was also a footballer who played for Cruz Azul during both the club's amateur and professional eras.

Muciño Martínez was part of the squad which won the club's promotional title in the 1963–64 season and subsequently played in the Primera División de México.

Cruz Azul went on to win the México 1970 competition, with Muciño netting a total of 14 league goals at the end of the season.

[21] At approximately 11 on night of 30 May 1974, Muciño met with 3 friends and their dates at Carlos O' Willys, a fine dining restaurant frequented by wealthy patrons located in Guadalajara.

Purportedly a fan of Guadalajara's rival team Atlas, Muldoon Barreto recognized Muciño and walked towards his table and began to discuss football with him.

Eventually, Muldoon Barreto began to antagonize and hurl insults towards Muciño and his date which escalated into a physical altercation between the two men.

[31][32] According to Muciño's son, a month or two after the murder occurred, Jaime Antonio Muldoon Barreto left Mexico for Spain, where there did not exist an extradition treaty between the two countries.

When he returned to Mexico in 1980, Muldoon Barreto's lawyers cited poor mental faculties as reason he was unfit to stand trial.

[4][31][29] Jaime Antonio Muldoon Barreto (born 1942) was a mechanical-electrical engineer who belonged to a wealthy architecture and real estate family based in Guadalajara.