Help me identify a certain children's book?

Question

Here's hoping someone would know what I'm talking about.
I'm looking for some children's books, but I do not remember the author or the name of the books. Here's what I know:-
-I read them some time in the 80s.
-They were a detective series, with a girl and a boy (with glasses, I think) that solves random little mysteries.
-For each mystery, the reader can guess along with the main characters as well, by finding clues in the story and usually a drawing they have of the crime scene and/or some important clue.
-Then the conclusion of the mystery is written bacwards, which you can read via the use of a mirror.
-One particular mystery as I remember concerns a runner in a marathon/race. One of the vital clues was an illustration of the runner - which if you looked closely, had running shoes with three stripes instead of the supposed two. Somehow that meant that it was a different runner or something, which solves the mystery.

So, anyone have ANY ideas on the name and author?

Answer 1

The Secret of the Loon Lake Monster and Other Mysteries by M. Masters (Paperback - Mar 1984)

Hawkeye Collins and Amy Adams in The Secret of the Loon Lake Monster and Other Mysteries (Piccolo Mysterysolvers) by M. Masters (Paperback - 1985)

n The Secret of the Loon Lake Monster (Spotlight, ISBN: 978-1-59961-146-4), Hawkeye Collins and Amy Adams are faced with nine mysteries that you have to help solve. The mysteries are The Case of the Bragging Boyfriend, The Case of the Splattered Sheets, The Mystery of the Telltale Timepiece, The Case of the Computer Cutup, The Secret of the Loon Lake Monster, The Case of the Nabbed Necklace, The Secret of the Concealed Cash, The Mystery of the Midnight Trickster, and The Case of the Camera Snatcher.

Answer 2

Encyclopedia Brown series! I loved those as a kid. The books are written by Donald Sobol.

Answer 3

No but It sounds great. I hope someone out there knows. I'd love to read it

Answer 4

encycolpedia brown