<PAGE>
-----------------------------
OMB APPROVAL
-----------------------------
OMB Number 3235-0145
Expires: October 31, 1994
Estimated Average burden
hours per response 14.90
-----------------------------
UNITED STATES
SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549
SCHEDULE 13G
Under the Securities Exchange Act of 1934
(Amendment No. 9)*
CHESAPEAKE BIOLOGICAL LABORATORIES, INC.
--------------------------------------------------------------
(Name of Issuer)
CLASS A COMMON STOCK
--------------------------------------------------------------
(Title of Class of Securities)
165146
-----------------------------
(CUSIP Number)
Check the following box if a fee is being paid with this statement [ ].
(A fee is not required only if the filing person: (1) has a previous statement
on file reporting beneficial ownership of more than five percent of the class
of securities described in Item 1; and (2) has filed no amendment subsequent
thereto reporting beneficial ownership of five percent or less of such
class.) (See Rule 13d-7).
*The remainder of this cover page shall be filled out for a reporting
person's initial filing on this form with respect to the subject class of
securities, and for any subsequent amendment containing information which
would alter the disclosures provided in a prior cover page.
The information required in the remainder of this cover page shall not be
deemed to be "filed" for the purpose of Section 18 of the Securities Exchange
Act of 1934 ("Act") or otherwise subject to the liabilities of that section
of the Act but shall be subject to all other provisions of the Act (however,
see the Notes).
Page 1 of 5 pages
<PAGE>
- -------------------- -------------------------
CUSIP No. 165146 Page 2 of 5 Pages
-------- --- ---
- -------------------- -------------------------
- --------------------------------------------------------------------------------
1 NAME OF REPORTING PERSON
S.S. or I.R.S. IDENTIFICATION NO. OF ABOVE PERSON
William P. Tew, Ph.D.
SS # ###-##-####
- --------------------------------------------------------------------------------
2 CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP*
(a) [ ]
(b) [ ]
- --------------------------------------------------------------------------------
3 SEC USE ONLY
- --------------------------------------------------------------------------------
4 CITIZENSHIP OR PLACE OF ORGANIZATION
United States
- --------------------------------------------------------------------------------
5 SOLE VOTING POWER
408,038 (as of December 31, 1996)
-----------------------------------------------------------------
NUMBER OF 6 SHARED VOTING POWER
SHARES
BENEFICIALLY
OWNED BY N/A
EACH -----------------------------------------------------------------
REPORTING 7 SOLE DISPOSITIVE POWER
PERSON
WITH 408,038 (as of December 31, 1996)
-----------------------------------------------------------------
8 SHARED DISPOSITIVE POWER
N/A
- --------------------------------------------------------------------------------
9 AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON
408,038 (as of December 31, 1996)
- --------------------------------------------------------------------------------
10 CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES*
- --------------------------------------------------------------------------------
11 PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW 9
9.92% (as of December 31, 1996)
- --------------------------------------------------------------------------------
12 TYPE OF REPORTING PERSON*
IN
- --------------------------------------------------------------------------------
*SEE INSTRUCTION BEFORE FILLING OUT!
Page 2 of 5 pages
<PAGE>
Item 1 (a) Name of Issuer
- ---------- --------------
Chesapeake Biological Laboratories, Inc.
Item 1 (b) Address of Issuer's Principal Executive Offices
- ---------- -----------------------------------------------
11412 Cronridge Drive
Owings Mills, Maryland 21117
Item 2 (a) Name of Person Filing
- ---------- ---------------------
William P. Tew, Ph.D.
Item 2 (b) Address of Principal Business Office or if none, Residence
- ---------- ----------------------------------------------------------
c/o Chesapeake Biological Laboratories, Inc.
11412 Cronridge Drive
Owings Mills, Maryland 21117
Item 2 (c) Citizenship
- ---------- -----------
United States
Item 2 (d) Title of Class of Securities
- ---------- ----------------------------
Class A Common Stock, $.01 par value
Item 2 (e) CUSIP Number
- ---------- ------------
165146
Item 3 If this statement is filed pursuant to Rule 13d-1(b), or
- ------ ---------------------------------------------------------
13d-2(b), check whether the person filing is a:
-----------------------------------------------
Not Applicable
Item 4 Ownership
- ------ ---------
(a) Amount Beneficially Owned as of December 31, 1996:
408,038
(b) Percent of Class as of December 31, 1996:
9.92%
Page 3 of 5 Pages
<PAGE>
(c) Number of shares as to which such person has
(i) sole power to vote or to direct the vote
as of December 31, 1996:
408,038
(ii) shared power to vote or to direct the
vote:
Not applicable
(iii) sole power to dispose of or to direct
the disposition of as of December 31,
1996
408,038
(iv) shared power to dispose of or to direct
the disposition of:
Not applicable
Item 5 Ownership of Five Percent or less of a Class
- ------ --------------------------------------------
Not applicable
Item 6 Ownership of more than Five Percent on Behalf of
- ------ -------------------------------------------------
Another Person
--------------
Not applicable
Item 7 Identification and Classification of the
- ------ ----------------------------------------
Subsidiary which Acquired the Security Being
--------------------------------------------
Reported on by the Party Holding Company
----------------------------------------
Not applicable
Item 8 Identification and Classification of Members of
- ------ -----------------------------------------------
the Group
---------
Not applicable
Item 9 Notice of Dissolution of Group
- ------ ------------------------------
Not applicable
Item 10 Certification
- ------- -------------
Not applicable.
Pages 4 of 5 Pages
<PAGE>
SIGNATURE
---------
After reasonable inquiry and to the best of my knowledge and belief, I
certify that the information set forth in this statement is true, complete
and correct.
February 13, 1997 ----------------------------
- ----------------- William P. Tew, Ph.D
Date
Pages 5 of 5 Pages
