By Ben Klayman and David Bailey

(Reuters) - Evidence from an autopsy on Sandra Bland, the black woman found hanging dead in a Texas jail days after a traffic stop, supports the medical examiner's initial ruling of suicide, a county prosecutor told reporters on Thursday.

The preliminary results also found high levels of marijuana in Bland's system, although officials are seeking additional tests to confirm when and how much she might have smoked or swallowed, Waller County Assistant District Attorney Warren Diepraam said.

"The evidence that we reviewed up to this point supports those findings," he said of the initial suicide ruling.

Bland was pulled over on July 10 near Prairie View, Texas, northwest of Houston, for failing to signal a lane change. After the incident escalated into an altercation between her and the white trooper, Bland was taken into custody and charged with assaulting an officer. She was found hanging in her jail cell on July 13 with a plastic trash bag around her neck.

Bland's traffic stop and subsequent death have been taken up by activists who say the case is the latest example of racial bias and excessive force by U.S. law enforcement.

Bland's family previously acknowledged a Facebook post by the 28-year-old Chicago-area native in which she discussed struggling with depression, but it disputed the suicide ruling.

While officials have said they are handling the investigation like a murder probe, they announced on Thursday there was no evidence in the autopsy to support a finding of murder. But the plastic trash bag was being tested further.

Diepraam said it was unclear whether Bland ingested marijuana before or after she was jailed.

Waller County Sheriff Glenn Smith, whose office operates the jail where Bland died, searched her cell for evidence of marijuana and found nothing, Diepraam said.

However, he added that the high level of the drug in Bland's system could have influenced her mood while in jail.

"It is a mood amplifier, so it is relevant in our opinion to determine whether or not marijuana may have played a role in her death as well, exacerbating existing conditions," he said.

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Bland had lacerations and abrasions on her wrists that could have been received when she was handcuffed during her arrest, he said. She also had about 30 healing cuts on her left arm that occurred two to four weeks before, he said.

An attorney for the Bland family, Cannon Lambert, before Diepraam's press conference called the autopsy "defective."

"The family's confidence is shaken by the continued discrepancies that are surfacing," Lambert said in an email.

Waller County officials said another autopsy was not needed, just further testing of evidence.

Bland's body was returned to the Chicago area on Wednesday in preparation for a funeral on Saturday.

NOT VIEWED AS SUICIDE RISK

Smith told Reuters on Wednesday that the jailers on duty when Bland was admitted felt she was not a suicide risk based on their observations and her statement on the questionnaire that she was not suicidal at the time.

However, according to the questionnaire, Bland also marked that she had tried to commit suicide last year by taking pills after the loss of a baby. She also said she had epilepsy.

Bland's full autopsy and toxicology reports may be released on Friday.

The jail where Bland died was cited three days after her death by the Texas Commission on Jail Standards for failing to complete visual face-to-face observations of inmates every 60 minutes as required by state regulations.

Bland was being held alone in a cell designed for up to five women when she was found dead.

Bland made three calls from the jail the day after her arrest: to her sister, a local friend and a bail bondsman, said Trey Duhon, Waller County's administrative leader. The bondsman spoke to family members about arranging Bland's bail, but nothing came of that, Duhon said.

In the call to her friend, LaVaughn Mosley, Bland talked about having her bail set at $5,000, ABC-owned TV station KTRK reported.

"I’m still just at a loss for words, honestly, about this whole process, how this switching lanes with no signal turned into all of this I don’t even know," Bland said in the message, according to the Houston station. "Umm, But I am still here, so just call me back when you can.”

Reuters was not able to reach Mosley to confirm the voicemail.

(Reporting by Ben Klayman in Detroit, additional reporting by David Bailey in Minneapolis; Editing by Andrew Hay and Cynthia Osterman)