This article contains spoilers from The Secret History of Twin Peaks. If you have not read the book, it is strongly recommended you do not read this article.
Delbert "Dell" Mibbler was a long time assistant manager at Twin Peaks Savings and Loan.
In February 1989, Dell got into an argument with Pete Martell about the dimensions of two-by-fours. Pete eventually compared them to the fact that the dollar is not worth as much as it used to be, which made Mibbler understand.
The next month, Audrey Horne came to the bank and chained herself to the vault's gate in protest of the bank's connections to Catherine Martell's Ghostwood development project. She asked him for water, which he brought to her as Pete Martell and the previously-thought-to-be-dead Andrew Packard arrived.
Mibbler led them to a safety deposit box Packard had the key for, but inside was a bomb, blowing out the windows of the bank and killing Mibbler, along with Martell and Packard. Dell was less than a week away from retirement after 58 years of service. Mibbler's glasses flew into a tree outside of the bank.