There is no evidence to prove that either of these claims are true

They also suggest he could have been behind the DNC email hack

Online sleuths claimed he was on the way to the FBI when he was shot

Reward has been increased from $25,000 to $125,000

But his family say his cell phone, watch and wallet were found on his body

The mother of a Democratic National Committee staffer shot dead in Washington D.C. in August has again appealed for help to catch his killer.

Seth Conrad Rich, 27, was gunned down in the affluent Bloomingdale neighborhood in July while he was on the phone to his girlfriend.

With no clues, police initially offered a $25,000 reward, but the sum has now been upped to $125,000, as announced by Rich's mother, Mary Rich, during a press conference on Monday.

'You have two people who shot my son twice in the back. We're not going to stop until we find my son's murderer. We will find his murderer, but we need all of you,' she said.

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Murdered: Democratic National Committee staffer Seth Rich (pictured) was shot dead in Washington D.C. on July 11. No arrests have been made in the murder

'Please help us': Mary Rich pleaded for help from the public in finding her son's killer

Fox 5 News reported that Mrs Rich continued: 'Please, help us find who killed him.'

'He fought with them. They have bruises and they have blood on them. If you saw anything, please call police. If may be nothing, and it may be the lead we need.

'We want to bring this to closure.'

Police have said there had been numerous robberies in the area in the lead up to Rich's murder and suspect he may have engaged in a fight with his attackers.

Mrs Rich said her son was always wary of his surroundings and played it safe.

'Next time something like this happens, it might be someone you love, ' she warned in a previous press conference.

'The only thing I can say as a mother is it warms my heart that he lived such a great life, even though it was cut short,' she added. 'I can always hold on to that.'

The victim's father, Joel Rich (left), and GOP lobbyist Jack Burkman (right) also spoke at the press conference on Monday

Despite D.C. police suspecting a robbery, Rich's family said that nothing had been taken from their son.

The trail seems to have gone cold after the DNC staffer was killed on July 11.

Rich's body was found covered in bruises on the 2100 block of Flagler Place NW, but he still had his watch, cell phone and wallet on him.

A police report seen by DailyMail.com also states the circumstances surrounding Rich's homicide are 'unknown'.

The mystery surrounding his death has sparked a flurry of theories posted online, including claims that he was on his way to speak to the FBI when he was shot.

Mrs Rich had previously pleaded for people to come forward with information on what happened to her son. Police are yet to make any arrests

Flowers are left on the street near where Rich's bruised body was found in Bloomingdale

A mother's hearbreak. Mary Rich asks for help finding killers of her son Seth #sethrich @nbcwashington pic.twitter.com/g2sZg5ugfr — Jackie Bensen (@jackiebensen) August 4, 2016

There have also been suggestions he fed Wikileaks the 3,000 DNC emails that were released at the start of the party's convention last week.

Reddit user The_Donald also constructed a timeline that links Rich to the Clintons, as pointed out by Heat Street.

He said Rich developed a relationship with environmentalists supporting Bernie Sanders. They then suggest this relationship was somehow connected to Rich's death.

There is no evidence to suggest any of these claims are true.

Cops said Rich may have been the victim of an attempted robbery, but his family insist the killers didn't take anything from him

One of his roommates said Rich was likely walking home from his girlfriend's house when he was shot. Rich had rented an apartment with three roommates

DailyMail.com has contacted the FBI for comment.

Julian Assange suggested the DNC leak may have been the work of an insider.

But he told DemocracyNow he didn't know their identity, and wouldn't reveal if he did.

In an interview with Britain's ITV, he also suggested that anyone within the Democratic organization could have had access to the trove of emails.

Rich was killed on July 11, two days after he appealed on Facebook to end gun violence.

Those who knew him said Rich (pictured center) liked to stay up late either due to a busy work schedule or to socialize

He wrote: 'I reiterate back to people stop hating each other. Too much pain to process. We have to be better and defend each other more true.

'A life is exponentially valuable. I have family and friends on both sides of the law. Please, stop killing each other.'

His death came after a spate of robberies in the neighborhood and DC police are now investigating if the murder is connected to those.

According to Fox 5, just an hour before the shooting there was a violent robbery in the 900 block on N Street, where police said three suspects pistol whipped, beat, kicked and robbed three people.

There were no witnesses to Rich's shooting, police said.

The attack took place across the street from a convenience store on the 2100 block of Flagler Place NW, three blocks away from Howard University Hospital.

It was not far from where Rich lived in a brownstone with three or four roommates, according to the Washington Post.

Colleagues have paid tribute to Rich's infectious smile and strong work ethic. Rich, an avid Packers fan, is pictured above at an NFL game in his teams colors

One of his roommates told the Post that Rich was likely walking home from his girlfriend's house at the time.

Mr Rich, 68, told Daily Mail Online: 'He was a 27-year-old who wanted to make a difference. That's part of the reason he went into his line of work, helping with the political process.

'He had worked for candidates whose vision he felt was going to help the country get better.

'He was working on that now, and whether he ever wanted to run, I would not say no. He wanted to stay involved and he wanted to make a difference.

'What we're feeling is that his vision is going to be unfulfilled. He was so capable, he would have been able to make a difference, I think.'

Describing himself on LinkedIn, Rich wrote: 'I have an enormous interest in public service and working towards making the world a better place.'

Rich was killed on July 11, two days after he appealed on Facebook to end gun violence

Rich graduated with a BA in political science from Nebraska's Creighton University in 2011.

While studying, he worked for the US Census Bureau and the Nebraska Democratic Party, and interned for Senator Ben Nelson.

His first job out of college was as a research associate for the opinion research firm Greenberg Quinlan Rosner.

In 2014, he took up his position at the DNC, which starts its all-important convention on July 25.

Former DNC Chairwoman Debbie Wasserman Schultz paid tribute to Rich the day after his death.

'Our hearts are broken with the loss of one of our DNC family members over the weekend,' she said in a statement.

'Seth Rich was a dedicated, selfless public servant who worked tirelessly to protect the most sacred right we share as Americans — the right to vote. He saw the great potential of our nation and believed that, together, we can make the world a better place.

'He was a joy to have as a member of our team, and his talents, intelligence and enthusiasm will be deeply missed by the many friends, colleagues and coworkers who worked by his side in service to the highest ideals of our democracy.'

Rich lived in a brownstone with three or four roommates. It was close to where he was shot

Rich grew up in Omaha, where his family played a strong role in the Beth El Synagogue.

His grandfather was a founding member of the synagogue and his father was head of the congregation until recently.

Rich studied Hebrew at the synagogue, and traveled to Israel two years ago. His teacher paid tribute to Rich on Facebook, calling him 'a dynamic young man who loved his work at the DNC.'

The 27-year-old was described by friends as quiet, soft-spoken and focused on his work but with a comic streak.

'On the Fourth of July he wore a full American flag outfit,' one friend, who did not wish to be identified, said. 'If he went to a Redskins game he would wear entirely red and gold.

'He was a big Packers fan and when they played he would wear a 'Cheesehead'. Although he was quiet with his words, in that way, he was outgoing.'

Those who knew him said Rich liked to stay up late either due to a busy work schedule or to socialize.

The Metropolitan Police Department offers up to a $25,000 reward for information leading to an arrest and conviction.