On Oct. 2, she posted a sun-kissed selfie on Instagram. "It's Friday and the body knows it," she wrote in Spanish. But she was not luxuriating in the golden autumn morning. She had begun a 14-hour journey to meet one of her fans, the world's most notorious drug lord, Joaquin Guzman Loera, at his mountain hideout in northwestern Mexico.
Guzman, who was captured Friday after a shootout in the coastal city of Los Mochis in Sinaloa, may have seen a kindred spirit of sorts in del Castillo. Her portrayal of a merciless drug trafficker in the 2011 hit soap opera "La Reina del Sur," or "The Queen of the South," had clearly struck a chord.
After she addressed him on Twitter the following year and urged him to use his wealth for good, he sent her flowers. The contact flourished after his 2014 capture. He wanted his story on film, and he chose her to produce it.
When the American actor and producer Sean Penn heard of the connection, he asked del Castillo to arrange a meeting with the drug lord. According to Penn's rambling account of the trip, published by Rolling Stone on Saturday, del Castillo was his interpreter and even his driver as the pair traveled with two friends by small plane and then by truck into the mountains of the Golden Triangle, the neutral zone at the border of Sinaloa, Guzman's home state, and the states of Durango and Chihuahua.
Del Castillo, 43, is a strangely mute figure in Penn's tale. But she is sharply outspoken. In 2012, still flush from success in her role on "La Reina del Sur" as the drug lord Teresa Mendoza, del Castillo posted a letter on her Twitter account, a declaration of her philosophy, tastes and beliefs.
In the middle of her musing, del Castillo suddenly referred to Guzman by his nickname, "El Chapo," or "Shorty": "Today I believe more in Chapo Guzman than in the governments that hide the truth although it may be painful, who hide the cure for cancers, AIDS, etc, for their own benefit and wealth."
Then she addressed Guzman in capital letters. "Mr. Chapo, wouldn't it be cool if you began to traffic in what is good," she wrote, continuing, "In cures for diseases, in food for street children, in alcohol for the elderly in old peoples' homes that don't let them spend their last years doing whatever" they feel like.
She called on him to burn down brothels where women "are worth no more than a pack of cigarettes" and concluded the section by writing, "Come on, Don," using a Spanish term of respect. "You would be the hero of heroes. Let's traffic in love, you know how."
The letter created a stir on social media and drew criticism, but she stood by it. She was asked about it again after Guzman escaped from prison in July through a tunnel, a feat she called "crazy funny" from the red carpet at a film festival in Spain.
Before her star turn in "La Reina del Sur," a production by the Spanish-language television network Telemundo, a division of NBCUniversal and the Spanish network Antena 3, del Castillo rose through the stable of actresses nurtured by the giant Mexican network Televisa, appearing in their weepy soap operas. She then appeared in several films set on the U.S. border with Mexico and played a Mexican crime boss in the Showtime series "Weeds" in 2009.
The daughter of a Mexican film star, del Castillo was to married Luis Garcia, one of the country's soccer stars in the 1990s, and was linked to Televisa's owner Emilio Azcarraga Jean before he inherited the company.
Del Castillo is no longer welcome at Televisa. In November, after news broke that Mexico's first lady, Angelica Rivera, another former Televisa star, had bought a luxury home from a contractor closely linked to her husband, President Enrique Pena Nieto, del Castillo went public with her disbelief.
"I wouldn't have enough to buy myself a house of that size, maybe Mrs. Angélica does, I don't know," she told the reporter who broke the story of the house. "When I was at Televisa, I was one of the leading actresses, important in the company," she continued. "We would never have earned that kind of money."
Del Castillo may have more to say on the case. She is set to star in a Spanish-language Netflix drama this year - "Ingobernable" or "Ungovernable" - as a fictional first lady of Mexico.
Her character, Netflix said when it announced the series, is capable of "creating a president, leaving a president, and killing a president.