Arizona shooting suspect Jared Loughner had been known for using drugs according to friends, including marijuana and a little known, but increasingly popular hallucinogenic drug, salvia.
Authorities have not yet ascribed a motive for the January 8 shooting in Tucson, that killed 6 and injured 14. A criminal trial on murder and attempted murder may still be months away, as prosecutors build their case.
While some lawmakers have said Loughner's drug use should have disqualified him from buying a gun, no links have been made between his drug use and the shooting.
Friend Zach Osler, 22, said in a recent interview that Loughner would talk about using the hallucinogen, known formally as salvia divinorum.
He would say he was using it and he would talk about it and say what [it] would do to him and I was like, 'Dude that's screwed up,' Osler said.
The friendship ended two years ago, according to Osler.
Loughner was rejected from the U.S. Army in 2008 for admitting to drug use, a U.S. Army spokesman said in a published report. He never underwent tests but the spokesman did not say what drugs Loughner said he had used.
High school classmate Grant Wiens, 22, has previously said Loughner smoked pot but didn't know how regularly, according to a report.
Friend Bryce Tierney, 22, said in a recent report that Loughner stopped using drugs in 2008 and started working out more.
I don't think substances had anything to do with this (shooting), he said. He and Loughner were arrested for possession of drug paraphernalia after authorities found the items in Tierney's van, although the charges were later wiped from both persons' records.
The herb, which is a type of mint, is common to southern Mexico and Central and South America, according to the National Institute on Drug Abuse.
In Oaxaca Mexico, the drug - which also goes by the name of Diviner's Sage -had been used by the Mazatec Indians for rituals and healing. Traditionally, the drug was consumed by chewing its leaf or drinking extracted juices but it can also be smoked as a joint, NIDA notes.
Salvia's most recent high profile use came from teen popstar Miley Cyrus of Hannah Montana fame, who was seen in a YouTube video inhaling the drug's smoke from a pipe.
A search for salvia on the YouTube website turns up hundreds of videos of people ingesting and experiencing the drug.
The Internet is used for the promotion and distribution of the drug, according to the federal Drug Enforcement Administration.
Its effects - which usually last between 1 and 30 minutes - include hallucinations or episodes that mimic a psychosis, known as psychotomimetic episodes.
For the user, effects can include psychedelic-like changes in visual perception, mood and body sensations, emotional swings, feelings of detachment, and a highly modified perception of external reality and the self, leading to a decreased ability to interact with one's surroundings, NIDA says.
Long term effects have not been investigated systematically.
About 1.8 million people ages 12 and up said they had used the drug but the most common users were those between the ages of 18 and 25, according to a 2008 report by the National Survey on Drug Use and Health Report.
NIDA says the drug has been used for the first time by 5.7 percent of high school seniors.
The drug is not regulated at the federal level but 24 states have passed laws controlling it, including restrictions on distribution, as of September last year.
It is also sold - in seed, leaf and liquid extract form of various strengths - in local outlets such as tobacco shops and stores that sell drug paraphernalia
The DEA currently lists salvia as a drug of concern and is considering classifying it as a Schedule I drug, like LSD or marijuana.