ATLANTA (AP) — Most of the people killed by Georgia police officers in 2017 and 2018 had drugs in their system, including cocaine, meth and marijuana, state officials say.

The Atlanta Journal-Constitution reports data obtained shows that out of 61 people killed by officers, 40 tested positive for a variety of drugs.

Testing that detects drugs was either not completed or not submitted to the Georgia Bureau of Investigation for six of the autopsies done on the people killed.

In 2017, 30 Georgians were shot to death by Georgia officers and one person was killed by a Taser, according to the GBI.

So far in 2018, at least 30 people have already been shot to death by officers in the state.

With the number of deadly officer-involved shootings in Georgia on track to double 2017's total, Georgia Bureau of Investigation Director Vernon Keenan said law enforcement leaders are looking for answers.

Keenan said drugs are a key issue in police shootings.

But data from the autopsies does not indicate what role the drugs played in the encounters with police.

Toxicology testing is a routine part of autopsies conducted by the GBI in use-of-force cases involving officers. Though every use of force case is different, experts believe drugs and mental health are two factors fueling the increase in number of officer-involved shootings, the newspaper reported.

"Drugs are a factor in a majority of the cases," GBI spokeswoman Nelly Miles said.

Marijuana was the most popular drug used by those in deadly altercations with police, followed by amphetamines and methamphetamines. Sixteen people tested positive for marijuana and 14 had amphetamines or meth in their system, records showed.

"When you talk about volume, there's more meth out there than anything else except marijuana," Miles said. "Methamphetamine does cause people to respond violently."

Not all of the drugs found in those killed by officers were illicit, though the quantities found during toxicology testing were not released. Various prescription drugs, including the pain medication Tramadol, the sedative Alprazolam (commonly known as Xanax), and Haloperidol, an antipsychotic medication, were also found in some investigations.

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Information from: The Atlanta Journal-Constitution, http://www.ajc.com