Exhibit (a)(1)(C)

Notice of Guaranteed Delivery

for

Offer to Purchase for Cash

All Outstanding Shares of Common Stock

of

Guidance Software, Inc.

at

$7.10 Net Per Share

by

Galileo Acquisition Sub Inc.

a wholly-owned subsidiary of

Open Text Corporation

THE OFFER AND WITHDRAWAL RIGHTS WILL EXPIRE AT 12:00 MIDNIGHT, EASTERN TIME, ON SEPTEMBER 6, 2017, UNLESS THE OFFER IS EXTENDED OR EARLIER TERMINATED.

Do not use for signature guarantees

This form of notice of guaranteed delivery must be used to accept the Offer to Purchase, dated August 8, 2017 (as it may be amended or supplemented from time to time, the “Offer to Purchase”) of Galileo Acquisition Sub Inc., a Delaware corporation (“Purchaser”) and a wholly-owned subsidiary of Open Text Corporation, a corporation incorporated under the federal laws of Canada (“OpenText”) to purchase all shares of common stock of Guidance Software, Inc., a Delaware corporation (“Guidance”), par value $0.001 per share (each, a “Share”), that are issued and outstanding, at a price of $7.10 per Share, in cash, without interest, and net of applicable withholding of taxes, upon the terms and subject to the conditions set forth in the Offer to Purchase and in the related Letter of Transmittal (which, together with any amendments or supplements thereto, collectively constitute the “Offer”) enclosed herewith, if certificates for Shares and all other required documents cannot be delivered to Computershare Trust Company, N.A. (the “Depositary”) prior to the Expiration Time (as defined in Section 1 of the Offer to Purchase), if the procedure for delivery by book-entry transfer cannot be completed prior to the Expiration Time, or if time will not permit all required documents to reach the Depositary prior to the Expiration Time.

Such form may be delivered by hand or transmitted by facsimile transmission or mailed to the Depositary and must include a guarantee by an Eligible Institution (as defined below). See Section 3 of the Offer to Purchase.

The Depositary for the Offer Is:

If delivering by mail:	If delivering by Facsimile Transmission:	If delivering by hand, express mail, courier, or other expedited service:
Computershare c/o Voluntary Corporate Actions P.O. Box 43011 Providence, RI 02940-3011	(Eligible Institutions only) (617) 360-6810 Confirm Facsimile Receipt by Telephone: (781) 575-2332	Computershare c/o Voluntary Corporate Actions 250 Royall Street, Suite V Canton, MA 02021

DELIVERY OF THIS NOTICE OF GUARANTEED DELIVERY TO AN ADDRESS OTHER THAN AS SET FORTH ABOVE, OR TRANSMISSION OF INSTRUCTIONS VIA FACSIMILE TO A NUMBER OTHER THAN AS SET FORTH ABOVE WILL NOT CONSTITUTE A VALID DELIVERY.

This Notice of Guaranteed Delivery is not to be used to guarantee signatures. If a signature on a Letter of Transmittal is required to be guaranteed by an Eligible Institution under the instructions thereto, such signature guarantee must appear in the applicable space provided in the signature box on the Letter of Transmittal and must be mailed (not faxed) to the Depositary in accordance with the instructions contained in the Letter of Transmittal.

The guarantee on page 4 must be completed.

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Ladies and Gentlemen:

The undersigned hereby tenders to Galileo Acquisition Sub Inc., a Delaware corporation (“Purchaser”) and a wholly-owned subsidiary of Open Text Corporation, a corporation incorporated under the federal laws of Canada (“OpenText”), upon the terms and subject to the conditions set forth in the Offer to Purchase, dated August 8, 2017 (the “Offer to Purchase”), and the related Letter of Transmittal (which, together with any amendments or supplements thereto, collectively constitute the “Offer”), receipt of which is hereby acknowledged, the number of shares of common stock, par value $0.001 per share (the “Shares”) of Guidance Software, Inc., a Delaware corporation (“Guidance”), indicated below pursuant to the guaranteed delivery procedure set forth in Section 3 of the Offer to Purchase.

Number of Shares Tendered:

Share Certificate Number(s) (if available):

If Shares will be delivered by book-entry transfer:

Name of Tendering Institution:

DTC Participant Number:

Transaction Code Number:

Date:             , 201    

Name(s) of Record Owner(s):

(Please Type or Print)

Address(es):

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(Including Zip Code)

Area Code and Telephone Number:

Signature(s):

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GUARANTEE

(Not to be used for signature guarantee)

The undersigned, a member in good standing of a recognized Medallion Program approved by the Securities Transfer Association Incorporated, including the Security Transfer Agents Medallion Program, the New York Stock Exchange Medallion Signature Program and the Stock Exchanges Medallion Program (each, an “Eligible Institution”), hereby guarantees that either the certificates representing Shares tendered hereby, in proper form for transfer or timely confirmation of a book-entry transfer of such Shares into the Depositary’s account at The Depository Trust Company (pursuant to the procedures set forth in Section 3 of the Offer to Purchase), together with a Letter of Transmittal (or a manually signed facsimile thereof), properly completed and duly executed, with any required signature guarantees (or, in the case of a book-entry transfer, an Agent’s Message (as defined in the Offer to Purchase)) and any other documents required by the Letter of Transmittal, will be received by the Depositary at one of its addresses set forth above within three NASDAQ Capital Market trading days after the date of execution hereof.

The Eligible Institution that completes this form must communicate the guarantee to the Depositary and must deliver the Letter of Transmittal, Share Certificate(s) and/or any other required documents to the Depositary within the time period shown above. Failure to do so could result in a financial loss to such Eligible Institution.

Name of Firm:
Address:
	(Including Zip Code)
Area Code and Telephone Number:
Authorized Signature:
Name:
	(Please Type or Print)
Title:
Dated:

NOTE: DO NOT SEND SHARE CERTIFICATE(S) WITH THIS NOTICE OF GUARANTEED DELIVERY. SHARE CERTIFICATE(S) ARE TO BE DELIVERED WITH THE LETTER OF TRANSMITTAL.

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