In July 2010 Albert Arriaga was arrested in Los Angeles in a U.S. Drug Enforcement Agency meth bust and handed over the Los Angeles Police Department. Then he died. A coroner subsequently found that his ribs had been broken in 21 places.

Here's how the Los Angeles Times describes Arriaga's last hours:

The informant, wired with a hidden microphone, approached the suspects' car and received the drugs from Alberto Arriaga, who remained in the passenger seat throughout the exchange. Drug agents moved in and are believed to have pulled Arriaga from the car, laid him face down on the pavement and handcuffed him, according to the LAPD report. Eventually, officers from the LAPD were called in to take Arriaga and the other suspect to a nearby station to be booked, the report said. A station supervisor asked the men if they had any medical issues. Arriaga complained of leg pain from a previous injury but mentioned nothing else, the report found. The men were then placed in a holding cell together. Sometime later that night, after the booking process had been completed, detention officers tried to move Arriaga, 45, to another jail facility. He told the jailers he was having abdominal pain "and had been beaten up by the DEA agents who arrested him," the report said. Arriaga was taken by ambulance to Hollywood Presbyterian Hospital. There, according to coroner's records, he waited 16 hours without receiving medical attention despite his worsening condition and then died. The coroner's autopsy revealed that Arriaga's fractured ribs had caused internal bleeding in his chest that led to respiratory failure. Because the ribs had been broken by "blunt force injuries" that came from the back, the coroner classified the death as a homicide.

The LAPD is tasked to investigate the circumstances behind the man's death. The problem? The DEA has refused for more than two years to allow its agents to be interviewed by the LAPD to try to determine where exactly Arriaga's injuries happened and who is ultimately responsible for his death:

Dawn Dearden, a spokeswoman for the DEA, said the U.S. Justice Department's own Office of the Inspector General is conducting an investigation into the death to determine whether DEA agents broke federal civil rights laws by using excessive force when arresting the man. Dearden said the DEA has provided the LAPD with some information and documentation about the incident. "However, it is not uncommon for an agent under multiple ongoing investigations to decline specific law enforcement interviews until an inspector general investigation is completed," she said.

The LAPD, though, are required to investigate any in-custody deaths and report their findings to a civilian panel. According to their report, no LAPD officers were present at Arriaga's arrest, so they have little information about how he was actually treated at the crime scene. Here's the reality:

Frustrated by the DEA's inaction, LAPD investigators went for assistance to local prosecutors in the district attorney's office, who concluded they did not have the authority to compel federal agents to cooperate with a local police department's investigation.

They can't compel federal agents to cooperate with the investigation even though the federal agents are actually subjects of the investigation.