They would use a vacuum cleaner wouldn't they and then sort through the dust for hairs.
Various collection methods exist. I don't know what method was used in this case.
http://crimeandclues.com/2013/04/05/trace-evidence-hair/Here are the hairs and where found;
mtDNA Number of Comparison with
profile Samples Recovered from reference samples
B 3 3 entrance hall
B1 1 1 entrance hall
-------------------------------------------------------
13 lounge
15 entrance hall
C 53 13 entrance to bedroom Kate Healy (Mother)
4 floor; bed next to window
1 bed of the child
7 floor; next to child's bed
-------------------------------------------------------
D 1 1 lounge
D1 1 1 entrance to bedroom
D1 1 1 floor; bed next to window
-------------------------------------------------------
F 3 1 lounge
2 entrance hall
-------------------------------------------------------
G 1 1 lounge Matthew Oldfield
I 1 1 entrance hall David Payne
-------------------------------------------------------
1 floor; bed next to window
J 3 1 entrance hall
1 floor; next to child's bed
-------------------------------------------------------
K 14 1 Residencia Liliana
13 vehicle(envlps 1,3,4,5 and 6)
-------------------------------------------------------
1 spot on bedspread
L 8 1 entrance to bedroom
2 entrance hall
4 floor; bed next to window
-------------------------------------------------------
M 48 13 vehicle (envlps 1,2,3 and 4)
35 Residencia Liliana Robert Murat
-------------------------------------------------------
2 lounge
11 entrance hall
N 24 6 entrance to bedroom Gerald Mccann
2 floor; bed next to window
3 floor; next to child's bed
-------------------------------------------------------
0 2 1 lounge
1 entrance hall Russell O'Brien
-------------------------------------------------------
Q 2 1 entrance hall
1 lounge
http://www.mccannpjfiles.co.uk/PJ/PORTUGUESE-FORENSIC.htm