El Paciente Interno is a 2012 Mexican documentary film directed and produced by Alejandro Solar Luna. This widely acclaimed film offers a deep-dive investigation into an assassination attempt that happened back in 1970. Although constructed as a documentary, the cinematic techniques employed by the director effectively blur the line between fiction and reality, evoking a sense of suspense usually featured within mystery and thriller genres.

The movie chronicles the life of Carlos Enrique Lehder Rivas, who was the internal patient or "El Paciente Interno". Lehder, a Colombian national, was convicted for attempting to assassinate Luis Echeverría Álvarez, the then President of Mexico in 1970.

El Paciente Interno not only covers the details of the assassination attempt but also explores the potential political consequences. It brilliantly uncovers the historical context that surrounds it and the subsequent personal consequences for Lehder. The attempt on the President's life was led by Lehder driving a car bomb into Echeverría's motorcade. While the assassination attempt failed, Lehder was subsequently arrested and sentenced to 28 years in prison.

As a major subset of the plot, the director tries to present Lehder’s post-prison life. After serving 20 years in a Mexican prison, Lehder found himself navigating a life filled with psychological, physical, and emotional obstacles. The director's meticulous process of tracking down Lehder, interviewing him, and weaving the testimony into the narrative lens brings a compelling richness to the story that engages with the audience on multiple levels. This focus on the human aspect propels the movie to be much more than just a historical documentation.

The film successfully humanizes Lehder, who was considered a criminal and a terrorist by many. The audience is allowed to empathize with Lehder's life post-prison, including battling mental illness and homelessness while in exile. This exploration into the life of an infamous convict maintains equal balance with the crime’s political backdrop, making it an interesting biographical sketch, thriller, and political documentary all at once.

El Paciente Interno employs a variety of sources, including news footage from the time of the assassination attempt and subsequent trial, present-day interviews with Lehder, and observations of his daily life. His subjectivity is captured effectively with visual aesthetics that blend contemporary footage with archival material. The overall narrative is further enhanced by a well-thought-out soundtrack that echoes the cultural milieu and the gripping nature of the story.

One of the highlights of the film is director Luna's insightful investigation into Lehder’s personal life and psyche. In fact, a significant portion of the film is spent detailing his backstory, his motivations, and what led him down this path of radical action. In many ways, Lehder is portrayed as a product of his time – caught up in the tumultuous political climate that was prevalent across Latin America in the 1960s and 70s.

The film is largely centered in Mexico City, showcasing Lehder's life both before and after his arrest in the city's context. This not only involves the audience in a gritty, true-crime story but also provides a unique snapshot of a bygone era in Mexican history.

In conclusion, El Paciente Interno is an interrogative account that blends personal tragedy with political intrigue. Through the figure of Carlos Enrique Lehder Rivas, Alejandro Solar Luna presents a compelling narrative that delves into themes of political violence, systemic failure, and intricate human stories. While it's a documentary rooted in historical events, Luna manages to craft a narrative that transcends the linear progression typical of this genre.

Much like the title, which translates to 'The Inpatient', El Paciente Interno is a film that requires patience and curiosity. For those who appreciate intellectually challenging cinema, this film gifts a rich historical context, well-crafted narrative, and humanizing portraiture of a man often seen as a criminal. It's not just a snapshot of a singular event, but a broader look at the consequences and reverberating impacts of political violence on the individual and society at large. It's a must-watch for those interested in historical events or true crime delivered with cinematic finesse.