One of the most difficult skills in writing fiction is how to give your reader information without making it seem like you’re giving information.
A shortcut often used is for a character to be called into an audience with a superior or authority, who will have a file on the character from which they will quote and, sometimes, demand elaboration:
“You’ve been working undercover in narcotics for four years since you lost your wife and child, and now you want to work the homicide squad?
That is not a question. That’s an info dump. All the information above is already known to the person being questioned. Also, is it relevant to the story? If so, there are more subtle ways:
“Do you think homicide is less stressful than narcotics, Michael?”
“No, sir. I just want to get out of the undercover work.”
“You don’t seem to have a difficulty staying on the right side,” the commissioner said. “I know the temptations are sometimes, ehm, persuasive.”
“I haven’t been tempted for years, sir.”
“You were tempted before.”
“That changed, sir. Lily and Chantelle…”
The commissioner’s eyes softened. “It must’ve been hard on you, that we never caught the killers. We always thought it had something to do with the XXX case, but nobody talked.”
“I made my peace with it, sir.”
“So your application with homicide is not to gain access to the records, to see where we failed.”
“No, sir. Like I said–”
“You just want to get out from the undercover work. Even though you received two commendations.”
“I’m tired of play-acting, sir. I want to do some straight police work for a change.”
The commissioner nodded. “I’ll approve your application, Michael. Don’t let me down.”
“No, sir. I won’t. Thank you.”
“The change might involve a change of roster, so your free days will be suspended for a moment until the new roster…”
“I’ll still have next Wednesday off, don’t I?”
The commissioner smiled sadly. “Yes, Michael. Nobody would want to you to come in for work when you need to pay your respects.”
Michael sighed his relief. Visiting their graves was about the only thing he could do since they had been slain so senselessly. He rose and nodded at the commissioner for turning for the office door, hoping the commissioner’s remark had been a wild stab and not a clue visible in his face. Homicide detail would give him access to the records. And he would see where they’d failed to bring Lily and Chantelle’s killers to justice. He’d been biding his time for four years, he wouldn’t want to screw up now.
Only the last paragraph features true exposition, but since the reader’s interest should be piqued by the hints in the dialogue, the information isn’t dumped. Plus it leaves enough to the imagination to give the reader. Also, it’s possible to leave it off–the commissioner’s remark is enough hint that Michael might be tempted to do some investigating on his own.