There are two ways to find this cache: the easy way and the hard way.
When you get to the cache, be mindful of muggle activity in the area and PLEASE be gentle with the cache's camoflague. You'll need your own pen.
Congrats to jewilk1 for the FTF in the rain!
The Easy Way: Complete Two Adventure Labs
To get the coordinates for this cache, complete both the "Got a Clue?" and "Not a Clue!" adventure labs in Cook Park. To avoid a lot of extra walking, you should do both labs simultaneously, switching back and forth between them as you encounter waypoints. These two labs will take you on a tour of Cook Park, from one end to the other, as you play a virtual version of the classic board game, "Clue." You must solve the crime: who did it, with what weapon, and where.
The 6 suspects are Mr. Green, Col. Mustard, Mrs. Peacock, Professor Plum, Miss Scarlet, and Mrs. White.
The 6 possible weapons are a candlestick, knife, lead pipe, revolver, rope, and wrench.
The 9 possible locations are the ballroom, billiard room, conservatory, dining room, hall, kitchen, library, lounge, and study.
When you successfully answer a question at each waypoint, the detective shows you one or two cards that indicate the person, weapon, and/or location you can eliminate from suspicion. Once you have seen 18 cards, use process of elimination to determine the three cards you haven't seen from the lists above. Pay attention to all the information in the journal entries; you'll need it to pass the checker. Enter the three pieces of required information into the certitude checker below to obtain the coordinates for this bonus cache. Use lower case letters only, with no punctuation, no capital letters, and no spaces between words.

You can validate your puzzle solution with certitude.
Once you've found this bonus cache, don't forget to mosey over to GC91NJV for the bonus to the other half of the adventure lab duo.
The Hard Way: Carmen Sandego's Spherical Geometry
Carmen Sandiego is not just the world's greatest super thief, she's also a globetrotting mastermind. As such, you are going to have to work hard to find her.
You can determine the coordinates without completing the adventure labs by finding information at 7 locations within Cook Park and then using that information to solve the equations below. After all, if you're going to circle the globe, you ought to know spherical geometry. You are NOT given waypoints for these locations; you must find them by searching the park. These waypoints are all within the boundaries of Cook Park, including the path to the west that some maps don't include as being in the park. (The west boundary is at 108th Ave.) You do not need to go into Durham Park or Tualatin Park. There is no hint available, nor is there a checker to confirm your solution. Good luck, or as Carmen would say -- See you next crime!
Carmen Sandiego's three assistants – Ruth Less, Joy Ryder, and Hardley Worthit – are on ships at sea, searching for clues to send back to Carmen at headquarters. When they were asked to report in, curiously, all of their three responses arrived at exactly the same time, which means that the minions are all exactly the same distance from headquarters, although in different directions. The minions are not necessarily the same distance from each other. First, figure out where each minion is located.
1. Find a bench with the name "Dean Donner" on it.
Let AA be the alphabetic value of the middle initial.
Let BB be Dean's age in years at death.
Let CC = BB + 20.
2. Find a bench with the name "Sook" on it.
Let D be the day of the month that the person was born.
Let E = D - 4.
Let F be the day of the month that the person passed away.
3. Find a bench with the name "Kuhn" on it.
Let GGGG be the first year mentioned.
Let HHH = GGGG - 1872.
Let IIII be the last year mentioned.
Let JJJ = IIII - 1844.
4. Find a sign with the word "Superior" and 6 different digits on it.
Let KK be the first two digits at the bottom of the sign.
Let LL = KK - 12.
Let MM be the last two digits.
Let NN = MM - 2.
5. Find a rock with the phrase "To Dad with Love" on it.
Let OOO be the troop number.
Let PP = OOO - 382.
6. Find a plaque with the name “James Dolan" on it.
Let QQ be the day of the month.
Let RR = QQ + 31.
7. Find the memorial to a "native Oregonian with an extraordinary love for nature."
Let SS be the day of the month that the person was born.
Let TT = SS + 29.
Let U be the day of the month that the person passed away.
Let V = U + 5.
Ruth Less at is N PP AA.983 W CC TT.550.
Joy Ryder is at N E F.133 W HHH RR.983.
Hardley Worthit is at N NN V.383 W JJJ LL.567.
Where in the world is Carmen Sandiego? She's holding the cache.