An Iowa newspaper reporter who exposed racist tweets by a charity fundraiser has found himself out of a job after his own offensive posts were uncovered.

Aaron Calvin, a journalist for the Des Moines Register, began looking into sports fan Carson King when his jovial plea for beer money turned into a national fundraiser for a children's hospital.

But his profile of Mr King led to a public backlash and the newspaper was forced to hire extra security after receiving threats.

Public scrutiny turned to Mr Calvin himself, who left the newspaper after it emerged he had made comments mocking same-sex marriage and used a racial slur.

Mr King gained national fame on September 14, when his hand-drawn sign for donations for his "Busch Light Supply" at an Iowa State University American football game was featured in the background of a TV broadcast.

He initially received around $600 (£488) from amused spectators but as donations topped $1 million (£814,650), Mr King said he would donate the money to a University of Iowa children's hospital.