Nijman is believed to have had connections with Willem Holleeder and other big names in the Dutch criminal underworld.

1994 was a good year for Hans, as he managed to gain knock-out victories over Mitsuya Nagai, Zaza Tkeshelashvili, Masayuki Naruse, Nikolai Zouev, and Dick Vrij.

He beat Lee Hasdell by submission at RINGS Holland on 2 February 1997 before losing to Kiyoshi Tamura in Japan on 25 October 1997.

[citation needed] Throughout his RINGS career, Nijman picked up victories over fighters such as; Masayuki Naruse Yoshihisa Yamamoto, Mikhail Illoukhine, Volk Han, Tsuyoshi Kohsaka and Kiyoshi Tamura.

[citation needed] On November 5, 2014, around 20:45, Nijman was shot dead whilst sitting in his 2013 Volkswagen Golf around the back of his Dutch Top Team gym "De Meer" in Beverwijk.

A half-hour after the shooting two cars, the Golf R32 and a taxi bus, were found burning to the ground in Velserbroek.