gum up

東野圭吾の小説 "New Comer" を読んでいます。

Kishida stared at Kaga with a look of incredulity. Uesugi, too, was taken aback. While it was standard practice to check the alibis of evryone closely associated with the victim, there was no reason to treat Kishida as a suspect. If Kaga pressed Kishida too hard for an alibi now, it might backfire and gum up the investigation later.

"gum up" を調べます。

・Collins Dictionary: To gum something up means to stop it working properly or efficiently.: Regulators may gum up an efficient system.
・Wiktionary: To cause to be gooey or gummy, especially with the effect of obstructing the operation of some mechanism or process.: The timer was digital, so there was no way to physically gum up the mechanism.
・The American Heritage® Dictionary of Idioms: Ruin or bungle something, as in The front office has gummed up the sales campaign thoroughly.

"gum" はガムテープのガムですね。