Standard kanji spelling; 繰り suggests 'twisting' or 'reading into' things.
勘ぐりUsage76%
Variant spelling using hiragana for the second part; less common but still seen.
かんぐりUsage8%
Etymology
Compound of 勘 (intuition, perception) and 繰り (from 繰る, to spin or reel), suggesting the act of spinning out suspicions from one's intuition. The exact historical derivation is uncertain.
