MIAMI-DADE COUNTY, Fla. – The 17-year-old daughter of a man who was found shot to death last week in his southwest Miami-Dade County home helped her boyfriend try to cover up the fact that he killed her father, police said.

Miami-Dade police said Demar Turruellas, 18, faces several charges, including second-degree murder, in the death of Evelio Gainza.

Gainza's body was found Thursday inside his home in the 1600 block of Southwest 141st Avenue after an out-of-state relative asked police to conduct a welfare check.

Police said the 63-year-old victim's 17-year-old daughter, Eveline Gainza, also faces charges of tampering with physical evidence and accessory after the fact.

"What is she doing? What was she thinking at that moment? What was she thinking? What was going through her mind?" Eveline Gainza's mother, Jacqueline Avila, told Local 10 News. "I had no idea what they were planning on -- what they were doing."

According to an arrest affidavit, Evelio Gainza's body was found in a second-floor bedroom, "concealed under multiple towels and bedding."

Police said he did not approve of his daughter's boyfriend.

Evelio Gainza, 63, was found dead Sept. 27 in his southwest Miami-Dade County home.

The couple had just moved back to Miami-Dade County from the west coast of Florida and were living with Avila.

Avila said her daughter had been studying to become a licensed practical nurse, but everything changed about a year ago when she met Turruellas.

"And all of the sudden she (met) this guy and life took another turn," Avila said. "Her father didn't want nothing to do with him."

According to the affidavit, Eveline Gainza asked her father to pick her up from her mother's home so that she could get her belongings. While Evelio Gainza was upstairs, Eveline Gainza snuck out of his home and took his car, picking up her boyfriend and driving him back to her father's place.

Turruellas then went upstairs, pulled out a gun and, unprovoked, shot Evelio Gainza in the back multiple times, the affidavit said.

Police say Eveline Gainza, 17, helped her boyfriend, Demar Turruellas, 19, hide evidence after he fatally shot her father.

After killing him, Turruellas and Eveline Gainza dragged the body to the master bathroom, which was under construction, and covered it with towels and blankets, the affidavit said.

"(Eveline Gainza) then cleaned the blood evidence at the scene by using bleach and paper towels, in order to conceal the evidence," the affidavit said.

Turruellas and Eveline Gainza collected all the shell casings from the room, placed them in garbage bags and then drove to an unknown location near Homestead, where they gave the gun to an acquaintance, the affidavit said.

Police said Eveline Gainza later told someone that she had taken her father to the airport and that he was traveling to Cuba.

"He did love her," Avila said. "But I can't understand why my daughter would go that path. I can't."