Hepworth formerly played for league clubs Castleford Tigers and Leeds Rhinos
Leeds Carnegie director of rugby Andy Key described their 19-12 victory at Nottingham as their best defensive performance of the season.
Jonny Hepworth scored Leeds' only try of the game, while fly-half Jason Strange added 14 points with the boot.
Key told BBC Radio Leeds: "We put massive pride in our defence and that won us this game.
"Our defence was outstanding and it was our best of the season. The boys showed unbelievable heart and desire."
The defeat was Nottingham's first at home this season, which effectively ends their slim title hopes.
For Leeds, they extend their lead at the top of National League One to five points after second-placed Exeter could only manage at 12-12 draw at home to Esher.
Exeter visit Headingley on Saturday, with Leeds knowing a win over their closest rivals could effectively have them promoted before Christmas.
Key added: "This win makes up for us not claiming a few try bonus points earlier this season against Doncaster and Exeter.
"It will be very hard against Exeter, but time is running out for teams to take our scalp and catch us up in the league.
"Our boys want to go back up it's as simple as that and that showed in the passion shown against Nottingham."
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