Donald Trump has become the first former US president to face criminal charges, for alleged hush money payments made to a porn star just before the 2016 presidential election.

But he is facing numerous lawsuits as well and it can be difficult to keep track of the investigations. Here are four that could have the biggest impact on him both personally and politically.

What's being investigated?

A grand jury has voted to indict the former president after New York prosecutors investigated a $130,000 pay-out to former adult star Stormy Daniels.

The charges have not yet been made public. Ms Daniels claims she and Mr Trump had sex, and that she accepted the money from his former lawyer before the 2016 election in exchange for her silence on the encounter.

Mr Trump has always denied they had sexual relations. 

Meanwhile, the business practices of his family company, the Trump Organization, are being examined by prosecutors.

Letitia James, the New York attorney general, is leading a civil investigation (which cannot result in criminal charges) and has spent years looking at whether the company committed various acts of fraud over several decades.

A criminal investigation is being led by the Manhattan District Attorney Alvin Bragg, and is looking at similar issues.

What has Trump said?

Mr Trump has described the indictment in the Stormy Daniels case as "political persecution" and said he doesn't expect a fair trial.

He is expected to appear in court on Tuesday, where he will be presented with the charges and enter a plea.

Separately, the former president and his lawyers have insisted the allegations against the Trump Organization are politically motivated.

Mr Trump has repeatedly criticised both Ms James and Mr Bragg.

So how serious is it?

Although details of the charges in the Stormy Daniels case are yet to be disclosed, it will be the first criminal case ever brought against a former US president.

The criminal investigation into the Trump Organization has already yielded convictions. The company was found guilty in December of fraud and falsifying business records and fined $1.6m (£1.31m). Allen Weisselberg, the organisation's chief financial officer, was sentenced to five months in jail in January.

In the civil case, Ms James has filed a lawsuit against Mr Trump and three of his children accusing them of "astounding" fraud and deception.

The lawsuit alleges that the family inflated their net worth by billions, and is seeking $250m (£226m) that was allegedly obtained through fraudulent means. It's also seeking bans on Mr Trump and his children from serving in a leadership role in any New York business.

A Manhattan judge has denied Mr Trump's bid to delay the trial, saying the scheduled date of 2 October is "written in stone".