LAS VEGAS (KLAS) — It’s been six years since Contessa Fitts has seen her niece Arianna.

Vanessa Murphy: Do you believe Arianna is alive?

Contessa Fitts:  I absolutely believe Arianna is alive. I believe that Arianna was taken because someone wanted her.

There is a nationwide search for the child and also a search for her mother’s killer.

“There’s no way Nikki deserved what happened,” Contessa said.

San Francisco police are working to solve the murder of Nicole Fitts while the FBI works to find Arianna.

“We don’t believe that Arianna was with Nicole at the time of Nicole’s death, but we do very much believe that the two are related,” said Katherine Zackel of the FBI’s San Francisco office.

Nicole Fitts was a single mom living in the San Francisco Bay area. Contessa says Nicole Struggled to make ends meet. She had lived with a self-proclaimed street pastor, Lemasani Briggs. She gave Briggs rent and babysitting money, but Contessa says Nicole was mistreated — verbally abused — and needed to leave.

“It was just really bad,” Contessa said.

She says Nicole crashed with friends and sometimes even slept at Best Buy where she worked. She also found new babysitters, relatives of Briggs — a couple, Helena and Devin Martin, and Helena’s sister Siolo Hearne.

“Nikki said the Martins and Siolo weren’t on speaking terms with Lemasani, so it kind of eased my concerns a little bit,” Contessa said.

Contessa later learned Helena Martin had spent time in prison about 20 years ago for killing her child’s father. She said it is unclear whether her sister knew that.

Nicole was focusing on her plan to find stable housing and daycare. She eventually found a new apartment with roommates.

“She bought a crib,” Contessa said. “She has furniture for Arianna, and she wants her daughter.” But Contessa said the babysitter wouldn’t return Arianna to Nicole.

Contessa Fitts:  That’s when things started to take a turn was when they started to claim that they no longer or that they weren’t available for Nikki to come and get her daughter. 

Vanessa Murphy: How frustrated was she?

Contessa Fitts: She was pretty frustrated.

Contessa says the last time she saw Arianna was in February of 2016 in Santa Cruz. The last time Nicole was seen was about two months later on April 1. 

Close friend and co-worker Michael Jacobo said he dropped her off at home.

“For a long time, at least three or four weeks, she was talking about bringing Arianna back home,” Jacobo said.

Her roommate, EJ Dalton, said she left shortly after.

 “There was a text sent from Nicole’s phone saying that she was in Fresno and that she was with a friend named Sam but nobody knows or has ever heard of this Sam person,” Dalton said.

And then there was a Facebook post: “with my 3-year-old. Needed this brake.”

“We knew that wasn’t right because Arianna was 2 and a half at the time and Nikki was really good with grammar and spelling,” Contessa said.

On April 8, 2016, police broke the news to Contessa.

“I don’t let him finish because I knew what he was going to tell me,” Contessa said, crying.

Nicole’s body was found in a shallow grave at a San Francisco park.

“How could this … how could this have happened?” Contessa asked.

An San Francisco Police Department forensic sketch artist portrays an age progression sketch of Arianna. (SFPD)

She said the search for Arianna began immediately with help from family, friends and strangers. But no word from the babysitters.

“That’s just kind of where the pieces of the puzzles were missing,” Contessa said.

One of the babysitters, Helena Martin, hired an attorney while investigators called for answers.

“They are the last persons that know her whereabouts,” according to a police commander.

Now, six years later, sources tell the 8 News Now I-Team all three babysitters, Helena and Devin Martin and Siolo Hearne have relocated to Las Vegas.

Contessa is following the trail and posting fliers. San Francisco police are offering a $100,000 reward for information, Best Buy is offering $10,000, and there are age progression sketches like this one.

Spokeswoman Katherine Zackel says the FBI has uncovered new leads over the past year.

Vanessa Murphy: Are the babysitters persons of interest or witnesses at this point?

Katherine Zackel:  I can’t talk about any specific individuals in this case due to FBI policy but what I will say is that we believe that there are multiple people who know more information than they have shared with law enforcement.

Vanessa Murphy: Do you believe the Martins killed your sister?

Contessa Fitts: I absolutely believe that they did. I absolutely believe it.  I, it doesn’t make any sense for these to be two isolated occurrences.

(National Center for Missing & Exploited Children)

While they hope for answers and arrests, Contessa pictures being reunited with Arianna, who would now be 8 years old.

“I do think about just that one day, that one day out of the blue that I get either a phone call or just someone showing up with her.  And just the biggest embrace there could ever be,” Contessa said.

I tried talking with the attorney representing Helena Martin. When I asked where Arianna could be since the babysitters were the last people she is known to be with, he said that’s attorney-client privilege.

When I asked if the Martins live in Las Vegas, he said that’s also attorney-client privilege.

And when I asked about whether the Martins cooperated with the investigation, he said he advised Helena Martin to not give any statements.

Anyone with information on Arianna’s whereabouts or the homicide of Nicole is encouraged to call the SFPD 24 Hour Tip Line at 1-415-575-4444, or text a tip to TIP411 and begin the text message with SFPD. You may remain anonymous.